Biomedical subjects

Richard E Redlinger

Publications and source records attributed to Richard E Redlinger.

6 recordsLinked to original sources

PubMed2005

Neuroblastoma-induced inhibition of dendritic cell IL-12 production via abrogation of CD40 expression.

BACKGROUND/PURPOSE: CD40 expression by dendritic cells (DCs) critically regulates their maturation/antitumor activity. CD40-CD40 ligand (CD40L) signaling stimulates DC-mediated IL-12 production/cytotoxicity. Recent studies suggest that neuroblastoma (NB)-derived gangliosides impair DC maturation, IL-12 secretion, and NK/T-cell activity. Neuroblastoma ganglioside-mediated abrogation of CD40 expression by DC and tumor-induced tolerance has not been studied. The purpose of this study is to determine if NB inhibits DC IL-12 production via CD40. The contributory role of the NB-derived ganglioside GM3 in this process is also examined. METHODS: Dendritic cells were generated from bone marrow of mice injected with saline (control) or murine NB. Control DCs were matured with or without GM3. Dendritic cells were cocultured with NB cells treated with or without a ganglioside synthesis inhibitor. Dendritic cell groups were analyzed for maturation/costimulatory markers. Control and tumor-derived DC were stimulated with CD40L or Staphylococcus aureus and studied for IL-12 expression. RESULTS: CD40 expression on DC generated from NB bearing mice decreased by 64% (P < .001). GM3 down-regulated DC maturation and CD40 expression. Only CD40-dependent IL-12 production was abrogated (60%, P < .01) in DC derived from NB-bearing mice. Dendritic cell capacity to synthesize IL-12 remained intact. CONCLUSIONS: Neuroblastoma-induced inhibition of DC function may result from ganglioside-mediated CD40 signaling deficiency. Strategies to bypass/augment CD40-CD40L signaling may improve current NB immunotherapies.

Animals↗

PubMed2004

Neuroblastoma and dendritic cell function.

Neuroblastoma, the most common extracranial solid tumor of childhood, remains a challenge for clinicians and investigators in pediatric surgical oncology. The absence of effective conventional therapies for most patients with neuroblastoma justifies the application of novel, biology-based, experimental approaches to the treatment of this deadly disease. The observation that some aggressive neuroblastomas, particularly in infants, may spontaneously regress suggested that immune-mediated mechanisms may be important in the biology of this disease. Advances in the understanding of the cognate interactions between T cells, antigen-presenting cells and tumors have demonstrated the sentinel role of dendritic cells (DC), the most potent antigen presenting cells, in initiating the cellular immune response to cancer. Until recently the function of DC in pediatric solid tumors, especially neuroblastoma, had not been extensively studied. This review discusses the role of DC in initiating and coordinating the immune response against cancer, the ability of neuroblastoma to induce DC dysregulation at multiple levels by inhibiting DC maturation and function, and the current vaccine strategies being designed to employ the unique ability of DC to promote neuroblastoma regression.

Animals↗

PubMed2003

Advanced neuroblastoma impairs dendritic cell function in adoptive immunotherapy.

BACKGROUND/PURPOSE: The authors previously described the complete regression of established neuroblastoma (NB) by the adoptive transfer of syngeneic interleukin-12 transduced dendritic cells (DC) from naive mice. However, some malignancies, like NB, abrogate DC immunostimulation. The authors hypothesize that IL-12 transduction of DC from NB-bearing mice will have the same antitumor properties. METHODS: A/J mice (n = 32) with established NB received peritumoral injection of 1 x 10(6) DC (DC, IL-12 DC, day 7 IL-12 DC or day 14 IL-12 DC) on day 7. Tumor growth, phenotype, and ability to induce NK and T cell activity were measured. RESULTS: Vaccination with naive admIL-12 DC resulted in 100% tumor regression and prolonged survival. Transduced DC induced only partial responses in 75% (day 7) and 25% (day 14) of animals. No differences in phenotype or effector cell activation were noted between admIL-12DC in tumor-bearing or naive mice. CONCLUSIONS: IL-12 DC from tumor-bearing animals have a decreased ability to induce antitumor activity against established murine NB. This decreased capacity appears to be related to the duration of exposure to tumor because day 14 transduced DC had less of an effect than day 7 DC, despite similar phenotypes and ability to activate immune effector cells.

Animals↗

PubMed2003

Cellular mechanisms of interleukin-12-mediated neuroblastoma regression.

BACKGROUND/PURPOSE: Interleukin-12 (IL-12) is a proinflammatory cytokine with potent antitumor effects. Previous studies from the authors laboratory showed regression of established neuroblastoma in mice vaccinated with IL-12 transduced dendritic cells (DC). Although regression was associated with intense T cell infiltration, the precise role of T cells is unknown. The purpose of this work is to study the cellular mechanisms in IL-12-mediated tumor regression. METHODS: Three groups of mice (n = 12) received subcutaneous inoculation with 1 x 10(6) murine neuroblastoma cells (TBJ). Anti-CD4 (T helper), anti-CD8 (T cytotoxic), or antiasialo-GM1 (natural killer) antibodies were injected intravenously at 3-day intervals to deplete various immune effector cell populations. Mice in each depletion group and the control (nondepleted) group were injected intratumorally on day 7 with 1 x 10(6) DC IL-12-transduced DC. Tumors were harvested for morphometry and immunohistochemistry at 21 days. RESULTS: CD4 depletion had no effect on tumor growth in either control or IL-12-vaccinated animals. In contrast, CD8-depleted animals treated with IL-12-transduced DC underwent initial regression followed by progressive tumor growth (P <.01). These tumors were smaller in size at the same time-point. However, NK cell depletion (antiasialo GM1) completely abrogated the antitumor effects of IL-12-transduced DC, leading to progressive tumor growth from the outset. There was no difference between the control and treated animals in this group. CONCLUSIONS: Contrary to our hypothesis that IL-12 DC primarily function to stimulate a T cell-mediated response, these data suggest that NK cells are essential for the initial antitumor response of animals treated with IL-12-transduced DC. CD8+ T cells appear to be necessary effector cells for complete rejection of tumor and possibly memory. NK cells are responsible for the early immune response. Furthermore, CD4+ (T helper) cells did not play any role in IL-12-induced regression. These results imply that for DC to generate an effective antitumor response against neuroblastoma both acquired and innate effector cells are required.

Animals↗

PubMed2003

Synergistic interleukin-18 and low-dose interleukin-2 promote regression of established murine neuroblastoma in vivo.

BACKGROUND/PURPOSE: Severe systemic toxicities have limited the clinical applications of the potent cytokine, interleukin-2 (IL-2). Recent studies have shown that IL-18 synergizes with IL-2 to enhance cytolytic activity in vitro. Combination therapy allows for IL-2 dose reduction, thus, limiting its toxicity while augmenting natural killer cell activity. The authors hypothesize that IL-18 plus low-dose IL-2 may induce a potent and sustained antitumor response in vivo providing effective immunotherapy for neuroblastoma. METHODS: Four groups of A/J mice (n = 28) were inoculated subcutaneously in the right flank with 1 x 10(6) murine neuroblastoma cells (TBJ). On day 7, 5 consecutive daily peritumoral injections were performed with saline (control), human rIL-2 (30,000 IU), murine IL-18 (1 microg), or IL-2 plus IL-18. Tumor growth was monitored, and animals with tumor progression were killed on day 21. Seven weeks after the initial treatment, animals with rejected tumors were rechallenged with 5 x 10(6) cells in the opposite flank. Quantitative data were analyzed by Student's t test. RESULTS: Rapid tumor growth and death was noted in all control animals by 21 days. Complete tumor eradication was seen in 28% of mice treated with IL-2 (P =.03), 42% of mice treated with IL-18 (P <.05), and 57% of mice treated with of IL-2 plus IL-18 (P <.05). Despite the initial response, all animals failed rechallenge and developed new or recurrent tumors within 7 to 10 days. CONCLUSIONS: Coadministration of low-dose IL-2 plus IL-18 induced a potent primary response to murine neuroblastoma likely caused by activation of natural killer cells in the tumor microenvironment. This combined cytokine therapy strategy was unable to induce sustained immunity to rechallenge. However, dendritic cell vaccination combined with IL-2 plus IL-18 cytokine treatment did allow for the establishment of a complete and durable antitumor response.

Adjuvants, Immunologic↗

PubMed2002

A novel bulk-culture method for generating mature dendritic cells from mouse bone marrow cells.

We established a novel culture method for generating dendritic cells (DC) from mouse bone marrow (BM) cells. Unfractionated bulk BM cells were cultured in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) for 5-7 days and a DC population was isolated by gradient centrifugation with 14.5% (w/v) metrizamide. Through this method, 30-40 x 10(6)/mouse DC with 85-95% purity was obtained on day 7; this yield was higher than those of conventional DC generated by Inaba's method either with GM-CSF alone (conventional-GM DC) or GM-CSF and IL-4 (conventional-GM/4 DC). Bulk-cultured DC have a more matured phenotype than both conventional-GM and -GM/4 DC as shown by higher expression of CD86, MHC class II and CD40. Functional analyses reveal that (1) bulk-DC show less ability in endocytosis than conventional-GM DC and are comparable in IL-12 p70 production with conventional-GM and -GM/4 DC. (2) Bulk-DC exhibit stronger stimulatory capacity in allogeneic T-cell proliferation than conventional DC. (3) By using ovalbumin (OVA) and OVA-specific T-cell receptor (TCR) transgenic mice (DO11.10) system, OVA protein-loaded bulk-DC stimulated CD4 T cells of DO11.10 mice more than conventional-GM DC and comparable with conventional-GM/4 DC. (4) Furthermore, OVA peptide-pulsed bulk-DC stimulated CD4 T cells more than conventional-GM and -GM/4 DC. These data indicate that bulk-DC are functionally more mature than conventional DC. Taken together, bulk-culture method is a simple technique for generating functionally mature BM-DC in large quantities and high purity.

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