Erratum: Ex vivo induction of antitumor DEC-205+ CD11c+ cells in a murine neuroblastoma model by co-stimulation with doxorubicin, lipopolysaccharide and interleukin-4.

[This corrects the article DOI: 10.3892/br.2015.546.].

Immune Checkpoint Inhibition Followed by Tumor Infiltration of Dendritic Cells in Murine Neuro-2a Neuroblastoma.

BACKGROUND: Most tumors responding to immunotherapy with monoclonal antibodies targeting programmed cell death protein1 (PD1) and programmed death ligand-1 (PD-L1) show surface expression of PD-L1. Neuroblastoma has been reported to show low PD-L1 surface expression. METHODS: The effect of immune checkpoint inhibitor on mouse neuroblastoma was investigated, and host immune cells were analyzed in the tumor microenvironment. Expression of co-stimulatory molecules by Neuro-2a mouse neuroblastoma cells was analyzed using flow cytometer. Neuro-2a cells were inoculated subcutaneously into A/J mice, followed by intraperitoneal injection of antibodies targeting PD-1 and PD-L1. Mice were sacrificed for the measurement of tumor weights on day 14 following tumor inoculation, and tumor-infiltrating cells were analyzed using a flow cytometer. RESULTS: Dim expression of PD-L1 was observed on the cell surface of cultured Neuro-2a cells. Growth of subcutaneous tumors was significantly suppressed, and PD-L1-expressing tumor cells were depleted by the antibody treatment. We confirmed that Neuro-2a cells opsonized by the anti-PD-L1 antibody were phagocytosed in the in vitro setting. In the treated tumor microenvironments, CD8α+ lymphocyte and CD11c+ MHC II+ cells were significantly accumulated in comparison with the control group. These CD11c+ MHC II+ cells expressed CD80, CD86, CD14, and CD40, but not CD205, PD-L1, or CTLA4. PD-1 expression was detected dimly. Immune suppressive effects of CD11b+Gr-1+ myeloid-derived suppressor cells by the administration of anti-PD-1 and PD-L1 antibodies were not observed in spleen, regional lymph nodes, or tumor microenvironment. CONCLUSIONS: Our findings raise the possibility that co-administration of anti-PD-1 and anti-PD-L1 antibodies have a synergistic effect on inhibition of tumor growth and could be an effective therapy against neuroblastoma with dim expression of PD-L1.

Chemoimmunotherapeutic effect of combined treatment with ex vivo generated antigen-presenting immune cells and conventional antitumor agents in a mouse neuroblastoma model.

PURPOSE: Combining antitumor immunotherapy with conventional intensive multimodal therapy may be considered for advanced neuroblastoma. We investigated combination therapy with ex vivo generated immunostimulatory cells and intraperitoneal doxorubicin. METHODS: Immunogenic death of neuro-2a neuroblastoma cells was induced by doxorubicin or cisplatin (negative control). Mouse bone marrow cells were cultured with granulocyte-macrophage colony-stimulating factor, followed by addition of doxorubicin-killed neuro-2a cells with or without interleukin-4 and/or CpG-oligodeoxynucleotide to induce immunostimulatory cells. CD8α+ lymphocytes were cocultured with killed neuro-2a cells and immunostimulatory cells, and interferon-γ was measured in the supernatant. Furthermore, female A/J mice were injected with viable neuro-2a cells, followed by immunostimulatory cells and doxorubicin. Then intraabdominal tumor nodules were evaluated. RESULTS: Bone marrow-derived immunostimulatory cells only promoted interferon-γ production by CD8α+ lymphocytes after first being stimulated by doxorubicin-killed neuro-2a cells and interleukin-4, followed by CpG-oligodeoxynucleotide. These cells had a surface antigen expression profile compatible with activated dendritic cells and suppressed tumors in mice intravenously injected with neuro-2a cells. Despite a similar surface antigen profile, the in vivo antitumor effect was stronger after injection of immunostimulatory cells induced by doxorubicin-killed neuro-2a cells compared with cells induced by cisplatin-killed neuro-2a cells. Moreover, interferon-γ production was greater when CD8α+ lymphocytes were cocultured with doxorubicin-killed neuro-2a cells and immunostimulatory cells rather than with cisplatin-killed cells. CONCLUSION: Cells with antitumor activity can be induced from bone marrow cells. Combining such cells with doxorubicin may activate antitumor immunity in tumor-bearing mice. Interactions between induced immunostimulatory cells and conventional chemotherapy might be important for antitumor immunity.

Ex vivo induction of antitumor DEC-205+ CD11c+ cells in a murine neuroblastoma model by co-stimulation with doxorubicin, lipopolysaccharide and interleukin-4.

The antigen-presenting capacity of specific cells and tumor immunogenicity involved in innate cellular immunity are important for initiating an antitumor response to advanced neuroblastoma. The present study was performed to establish a method of producing antigen-presenting cells that induced an immune response to murine neuroblastoma cells through culture with neuroblastoma cells that had undergone immunogenic cell death. Immunogenic death of neuro-2a murine neuroblastoma cells was induced by exposure to doxorubicin. Mouse bone marrow cells were cultured in medium containing granulocyte-macrophage colony-stimulating factor, followed by the addition of doxorubicin-treated neuro-2a cells to the culture with or without lipopolysaccharide (LPS) and/or interleukin-4. Subsequently, cluster of differentiation (CD) 8α+ lymphocytes were co-cultured with neuro-2a cells and the adherent bone marrow cells obtained by the above procedure to evaluate CD8α+ lymphocyte proliferation and interferon-γ production. Furthermore, the surface antigen profile of adherent bone marrow cells was analyzed by flow cytometry. When adherent bone marrow cells were treated with LPS and/or interleukin-4, followed by co-culture with CD8α+ lymphocytes and neuro-2a cells, interferon-γ production by the CD8α+ cells increased in response to anti-CD3/CD28 antibody stimulation. CD11c major histocompatibility complex II (MHC II) double-positive cells were increased among adherent cells derived from cultured bone marrow cells. These cells were positive for DEC-205, but not CD8α. These findings suggest that co-culture of bone marrow-derived cells with tumor cells (that have undergone immunogenic death by exposure to doxorubicin) plus stimulation by LPS and interleukin-4 induces antigen-presenting cells that can evoke an immune response to neuroblastoma. Bone marrow-derived DEC-205+ CD11c+ MHC II+ dendritic cells are key antigen-presenting cells in the induction of an immune response following phagocytosis of doxorubicin-treated neuroblastoma cells.

Phagocytosis of bafilomycin A1-treated apoptotic neuroblastoma cells by bone marrow-derived dendritic cells initiates a CD8α+ lymphocyte response to neuroblastoma.

This study aimed to determine whether bafilomycin A1 (Baf-A1), a vacuolar H-ATPase inhibitor, could promote an immune response after the induction of apoptosis in mouse neuroblastoma cells. Mouse neuro-2a cells were cultured in a medium containing Baf-A1, and apoptosis was evaluated by flow cytometry. To examine the influence in the phagocytic cell, CD11b spleen cells or bone marrow-derived dendritic cells (BM-DCs) were cocultured with Baf-A1-treated neuro-2a. Interferon-γ (IFN-γ) production was used as an index of the immune response, and CDDP was used as the negative control. When CD8α cells were cocultured with CD11b cells and Baf-A1-treated neuro-2a cells in the presence of CpG-oligodeoxynucleotide (CpG-ODN) (a toll-like receptor 9 [TLR-9] agonist), CD8α lymphocyte proliferation and secretion of IFN-γ were observed. Phagocytosis of apoptotic cells by BM-DCs was maximal after simultaneous stimulation with CpG-ODN and lipopolysaccharide (LPS; a TLR-4 agonist). IFN-γ secretion was maximal when Baf-A1-treated neuro-2a cells and CD8α lymphocytes were cocultured with BM-DCs and stimulated with CpG-ODN. In contrast, IFN-γ production was not increased when the cells were cultured with LPS. When cells were stimulated with both CpG-ODN and LPS, promotion of IFN-γ production by CpG-ODN was suppressed. Induction of apoptosis by Baf-A1 could possibly enhance antitumor immunity in patients receiving chemotherapy for neuroblastoma. Stimulation of BM-DCs with a TLR-9 agonist could promote antitumor activity after Baf-A1 treatment.

[Comparison of the chemoimmunotherapeutic effect of doxorubicin and bafilomycin-A1 in mouse neuroblastoma cells].

The aim of this study was to compare the ability of the drugs doxorubicin and Bafilomycin-A1(Baf-A1)to promote an immune reaction following the induction of cell death in a mouse neuroblastoma model. Neuro-2a cells were cultured in medium containing doxorubicin or Baf-A1. Bone marrow-derived dendritic cells(BM-DCs)were co-cultured with neuro-2A cells that were grown in doxorubicin- or Baf-A1-containing media, and phagocytosis of neuro-2a cells by the BN-DCs was evaluated. Additionally, dead neuro-2a cells were co-cultured with CD8a + lymphocytes and BM-DCs, and the proliferation of CD8a + cells was evaluated. Interferon-g(IFN-g)production was used as an indexof the immune response. Dead neuro-2a cells treated with doxorubicin were phagocytosed effectively compared to the cells treated with Baf-A1. However, phagocytosis of cells treated with Baf-A1 was promoted after stimulation with CpG oligodeoxynucleotide (CpG-ODN). When CD8a + cells were co-cultured with BM-DCs and doxorubicin-treated neuro-2a cells, CD8a + lymphocyte proliferation was observed. There was no statistical difference in IFN-g secretion between the doxorubicin-treated and Baf-A1-treated cells. However, after stimulation by CpG-ODN, IFN-g production was more effectively observed in the Baf-A1-treated cells. Induction of cell death by doxorubicin or Baf-A1 could possibly enhance antitumor immunity in patients receiving chemotherapy for neuroblastoma. Selection of anti-tumor agents and stimulation of BM-DCs with a toll-like receptor (TLR) agonist is considered important in promoting antitumor activity after chemotherapy.

Doxorubicin treatment induces tumor cell death followed by immunomodulation in a murine neuroblastoma model.

Chemotherapy of malignant tumors induces tumor cell death. Numerous antitumor agents induce apoptosis of tumor cells, which are subsequently engulfed by phagocytes, initiating an immune reaction. The induction of immunogenic cell death by antitumor agents may be advantageous for antitumor immunity. The purpose of this study was to determine whether doxorubicin is capable of inducing an immunogenic reaction in murine neuroblastoma cells. The murine neuroblastoma cell line (neuro-2a cells) was cultured in a medium containing doxorubicin or cisplatin (CDDP), and induction of cell death was confirmed by cell viability assays. Cluster of differentiation (CD)8α+ lymphocytes were co-cultured with neuro-2a cells that had died following treatment with either doxorubicin or CDDP, and CD11b+ spleen cells or bone marrow-derived dendritic cells (BM-DCs) were added to the culture. Proliferation of CD8α+ lymphocytes and interferon (IFN)-γ production were evaluated. When CD8α+ cells were co-cultured with doxorubicin-treated neuro-2a cells and BM-DCs, CD8α+ cells reacted to anti-CD3/CD28 antibody stimulation, proliferated and increased IFN-γ production. IFN-γ production was more effectively promoted by co-culture with doxorubicin-treated neuro-2a cells than by co-culture with CDDP-treated neuro-2a cells. These findings suggest that doxorubicin is capable of inducing immunogenic cell death in neuroblastoma cells, and thus has an immunological advantage for chemotherapy of neuroblastoma compared with CDDP. BM-DCs are considered to be the key antigen-presenting cells in the immune reaction following the induction of immunogenic neuroblastoma cell death and phagocytosis.

Regulatory mechanisms for the production of BAFF and IL-6 are impaired in monocytes of patients of primary Sjögren's syndrome.

INTRODUCTION: In this study, we investigated possible aberrations of monocytes from patients with primary Sjögren's syndrome (pSS). We focused on B-cell-activating factor of the TNF family (BAFF) and IL-6 because they are both produced by monocytes and are known to be involved in the pathogenesis of pSS. METHODS: Peripheral monocytes were prepared from both pSS patients and normal individuals. The cells were stimulated in vitro with IFN-γ, and the amounts of IL-6 and soluble BAFF (sBAFF) produced by the cells were quantitated. The effect of sBAFF itself on the production of IL-6 was also studied. To investigate the response of pSS monocytes to these stimuli, the expression levels of the genes encoding BAFF receptors and IL-6-regulating transcription factors were quantitated. RESULTS: Peripheral pSS monocytes produced significantly higher amounts of sBAFF and IL-6 than normal monocytes did, even in the absence of stimulation. The production of these cytokines was significantly increased upon stimulation with IFN-γ. The elevated production of IL-6 was significantly suppressed by an anti-BAFF antibody. In addition, stimulation of pSS monocytes with sBAFF induced a significant increase in IL-6 production. Moreover, the expression levels of a BAFF receptor and transcription factors regulating IL-6 were significantly elevated in pSS monocytes compared to normal monocytes. CONCLUSIONS: The results of the present study suggest that the mechanisms underlying the production of sBAFF and IL-6 are impaired in pSS monocytes. Our research implies that this impairment is due to abnormally overexpressed IL-6-regulating transcription factors and a BAFF receptor. These abnormalities may cause the development of pSS.

Reduced expression of TCR zeta is involved in the abnormal production of cytokines by peripheral T cells of patients with systemic lupus erythematosus.

Accumulating evidence suggests that dysfunction of T cells underlies the pathogenesis of systemic lupus erythematosus (SLE). We revealed that SLE T cells produced an abnormally excessive amount of IFN-γin vitro upon stimulation through TCR, and the expression level of TCR zeta was significantly reduced. The production of IFN-γ by SLE T cells was negatively correlated with the expression level of TCR zeta. This correlation was abolished when the cells were stimulated with TPA and ionomycin, which bypass TCR and introduce signals directly into the cells, but the production of IFN-γ by SLE T cells remained abnormally elevated. Taken together, these data suggest that regulatory mechanisms not only for the expression of TCR zeta but also for the production of IFN-γ were impaired in SLE T cells. These impairments may be responsible for the aberrant responses of SLE T cells and partly involved in the development of SLE.

Effect of interleukin-2 on synthesis of B cell activating factor belonging to the tumor necrosis factor family (BAFF) in human peripheral blood mononuclear cells.

B cell activating factor belonging to the tumor necrosis factor family (BAFF) is a cytokine, indispensable for B cell survival, maturation, and activation. Over-expression of BAFF leads to lupus like disease in mice and the serum level of BAFF is elevated in human lupus. However, little is known about BAFF synthesis and its regulation. In this study, we examined the effects of a series of inflammatory cytokines on BAFF production in human peripheral blood mononuclear cells (PBMCs) in vitro. We found interleukin-2 (IL-2) strongly and dose-dependently stimulated BAFF synthesis in PBMCs, and an anti-IL-2 antibody neutralized the effect. Furthermore, T and NK cells produced BAFF with IL-2 stimulation. From these observations, IL-2 is one of the regulatory cytokines having a positive effect on BAFF synthesis in human peripheral T and NK cells. Persistent over-production of IL-2 might lead to up-regulation of BAFF synthesis in PBMCs in pathological conditions such as lupus.

Conservative sequences in 3'UTR of TCRzeta mRNA regulate TCRzeta in SLE T cells.

We have demonstrated that T-cell receptor zeta (zeta) mRNA with a 562-bp deleted alternatively spliced 3'-untranslated region (3'UTR) observed in T cells of patients with systemic lupus erythematosus (SLE) can lead to a reduction in zeta and TCR/CD3 (J. Immunol., 2003 & 2005). To determine the region in zeta mRNA 3'UTR for the regulation of zeta, zeta mRNA with 3'UTR truncations ligated into pDON-AI was used to infect murine T-cell hybridoma MA5.8 cells, which do not contain zeta. As a Western blot analysis demonstrated the importance of the regions from +871 to +950, containing conservative sequence 1 (CS1), and +1070 to +1136, containing CS2, for the production of zeta, we constructed MA5.8 mutants carrying zeta mRNA 3'UTR with deletions of these regions (DeltaCS1 and DeltaCS2 mutants). Western blot and FACS analyses showed significant reduction in the cell surface zeta and TCR/CD3 in both these mutants, and IL-2 production was decreased, compared with MA5.8 cells transfected with wild-type zeta mRNA. Furthermore, real-time PCR demonstrated the instability of zeta mRNA with 3'UTR deletions in these MA5.8 mutants. In conclusion, CS1 and CS2 may be responsible for the regulation of zeta and TCR/CD3 through the stability of zeta mRNA in SLE T cells.

TCRzeta mRNA splice variant forms observed in the peripheral blood T cells from systemic lupus erythematosus patients.

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease of unknown etiology. Tyrosine phosphorylation and protein expression of the T-cell receptor zeta chain (zeta) have been reported to be significantly decreased in SLE T cells. In addition, zeta mRNA with alternatively spliced 3' untranslated region (zetamRNA/as-3'UTR) is detected predominantly in SLE T cells, and aberrant zeta mRNA accompanied by the mutations in the open reading frame including zeta mRNA lacking exon7 (zetamRNA/exon7-) is observed in SLE T cells. These zeta mRNA splice variant forms exhibit a reduction in the expression of TCR/CD3 complex and zeta protein on their cell surface due to the instability of zeta mRNA splice variant forms as well as the reduction in interleukin (IL)-2 production after stimulating with anti-CD3 antibody. Data from cDNA microarray showed that 36 genes encoding cytokines and chemokines, including IL-2, IL-15, IL-18, and TGF-beta2, were down-regulated in the MA5.8 cells transfected with the zeta mRNA splice variant forms. Another 16 genes were up-regulated and included genes associated with membranous proteins and cell damage granules, including the genes encoding poliovirus-receptor-related 2, syndecan-1, and granzyme A.

Aberrant expression of BAFF in T cells of systemic lupus erythematosus, which is recapitulated by a human T cell line, Loucy.

B cell-activating factor of the tumor necrosis factor (TNF) family, or BAFF, is mainly produced in monocytes and dendritic cells, and indispensable for proliferation, differentiation and survival of B cells. BAFF is a type II membrane-bound protein and the extracellular C-terminal fragment is released from the cells as soluble BAFF (sBAFF), which binds to specific receptors on B cells. Accumulating evidence suggests that BAFF plays an important role in the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE). In this study, we developed a sensitive sandwich ELISA system to quantify the amount of sBAFF using our own mAb. Treatment of peripheral T cells of SLE patients with an anti-CD3 antibody triggered robust expression of BAFF and subsequent release of sBAFF from the cells. On the other hand, the stimulus induced only marginal elevation of sBAFF from normal T cells. These data indicate that BAFF is expressed in T cells upon stimulation at least under pathological conditions. Expression of BAFF was also largely induced in a human T cell line, Loucy (American Type Tissue Collection CRL-2629), in response to several stimuli, while other T cell lines so far examined produced the cytokine almost constitutively. These data suggest that Loucy recapitulates some of the characteristics of SLE T cells. Investigation of molecular and cellular mechanisms of production of BAFF in Loucy demonstrated that expression of BAFF was regulated through a signal transduction pathway which involves c-jun NH2-terminal kinase and p38, and that shedding of BAFF was catalyzed by a membrane-bound protease, furin.

DNA microarray gene expression profile of T cells with the splice variants of TCRzeta mRNA observed in systemic lupus erythematosus.

We have reported that the TCRzeta mRNA with alternatively spliced 3' UTR (zeta mRNA/as-3'-untranslated region (UTR)) and zeta mRNA lacking exon 7 (zeta mRNA/exon 7-) observed in systemic lupus erythematosus patient T cells can lead to down-regulation of both zeta and TCR/CD3 complexes. To determine whether these T cells expressing decreased zeta exhibit differential transcription patterns, we transfected retrovirus vectors containing wild-type zeta cDNA, zeta cDNA/as-3' UTR, and zeta cDNA/exon 7- into murine T cell hybridoma MA5.8 cells which lack zeta expression to construct the MA5.8 mutants WT, AS3' UTR, and EX7-, respectively. FACS analyses demonstrated reduced cell surface expression of zeta and TCR/CD3 complexes on the AS3' UTR mutant and the EX7- mutant in comparison to that on the WT mutant. Total RNA was collected after stimulating the MA5.8 mutants with anti-CD3 Ab. Reverse-transcribed cDNA was applied to the mouse cDNA microarray containing 8691 genes, and the results were confirmed by real-time PCR. The results showed that 36 genes encoding cytokines and chemokines, including IL-2, IL-15, IL-18, and TGF-beta2, were down-regulated in both the AS3' UTR mutant and the EX7- mutant. Another 16 genes were up-regulated in both, and included genes associated with membranous proteins and cell damage granules, including the genes encoding poliovirus receptor-related 2, syndecan-1, and granzyme A. Increased protein expression of these genes was confirmed by Western blot and FACS analyses. Identification of these responsive genes in T cells in which the zeta and TCR/CD3 complexes were down-regulated may help to better understand the pathogenesis of systemic lupus erythematosus.

A splice variant of the TCR zeta mRNA lacking exon 7 leads to the down-regulation of TCR zeta, the TCR/CD3 complex, and IL-2 production in systemic lupus erythematosus T cells.

The reduction or absence of TCR zeta-chain (zeta) expression in patients with systemic lupus erythematosus (SLE) is thought to be a factor in the pathogenesis of SLE. We previously reported a splice variant of zeta mRNA that lacks the 36-bp exon 7 (zeta mRNA/exon 7(-)) and is accompanied by the down-regulation of zeta protein in T cells from SLE patients. In this study, we show that EX7- mutants (MA5.8 cells deficient in zeta protein that have been transfected with zeta mRNA/exon 7(-)) exhibit a reduction in the expression of TCR/CD3 complex and zeta protein on their cell surface as well as a reduction in the production of IL-2 after stimulation with anti-CD3 Ab, compared with that in wild-type (WT) mutants (MA5.8 cells transfected with the WT zeta mRNA). Furthermore, real-time PCR analyses demonstrated that zeta mRNA/exon 7(-) in EX7- mutants was easily degraded compared with zeta mRNA by the WT mutants. Pulse-chase experiment showed zeta protein produced by this EX7- mutants was more rapidly decreased compared with the WT mutants. Thus, the lower stability of zeta mRNA/exon 7(-) might also be responsible for the reduced expression of the TCR/CD3 complex, including zeta protein, in SLE T cells.

TCR zeta mRNA with an alternatively spliced 3'-untranslated region detected in systemic lupus erythematosus patients leads to the down-regulation of TCR zeta and TCR/CD3 complex.

The reduction or absence of TCR zeta-chain (zeta) expression in systemic lupus erythematosus (SLE) patients is thought to be related to the pathogenesis of SLE. Recently, we reported the predominant expression of zeta mRNA containing an alternatively spliced 3'-untranslated region (3'UTR; zetamRNA/as-3'UTR) and a reduction in the expression of zeta mRNA containing the wild-type 3'UTR (zetamRNA/w-3'UTR) in T cells from SLE patients. Here we show that AS3'UTR mutants (MA5.8 cells deficient in zeta protein that have been transfected with zetamRNA/as-3'UTR) exhibit a reduction in the expression of TCR/CD3 complex and zeta protein on their cell surface as well as a reduction in the production of IL-2 after stimulation with anti-CD3 Ab compared with that in wild-type 3'UTR mutants (MA5.8 cells transfected with zetamRNA/w-3'UTR). Furthermore, the real-time PCR analyses demonstrated that the half-life of zetamRNA/as-3'UTR in AS3'UTR mutants (3 h) was much shorter than that of zetamRNA/w-3'UTR in wild-type 3'UTR mutants (15 h). Thus, the lower stability of zetamRNA/as-3'UTR, which is predominant in SLE T cells, may be responsible for the reduced expression of the TCR/CD3 complex, including zeta protein, in SLE T cells.