Elimination of CD4(+) T cells enhances anti-tumor effect of locally secreted interleukin-12 on B16 mouse melanoma and induces vitiligo-like coat color alteration

EGR1 Mediated Reduction of Fibroblast Secreted-TGF-β1 Exacerbated CD8+ T Cell Inflammation and Migration in Vitiligo

Vitiligo is a T cell-mediated depigment skin disease caused by the complex interplay between melanocyte dysfunction, environmental stimulation, and dysregulated immune signals. Transforming growth factor-β1 (TGF-β1), which typically derives from regulatory T cells, has long been identified at low levels in the peripheral system of vitiligo patients. Here, through RNA-sequencing and transcription factor enrichment, we revealed that in response to CD8+ T cell-secreted interferon-gamma (IFN-γ), stromal fibroblast downregulates early growth response 1 (EGR1) activity, leading to TGF-β1 deficiency. The defective immune regulation loop further exacerbated local CD8+ T cell inflammation and promoted inflammatory cell migration in vitiligo. Thus, fibroblast-derived TGF-β1 plays an important stromal signal in vitiligo pathogenesis.

Serum Levels of IL-35, One of the Newest Members of Interleukin-12 Family of Cytokines, in Patients With Vitiligo

INTRODUCTION

Vitiligo is a chronic skin disorder in which immune dysregulation has been reported as one of the major etiopathological factors. Interleukin-12 (IL-12), IL-23 and IL-27 of IL-12 cytokine family were identified as critical cytokines in the pathogenesis of many autoimmune and inflammatory skin diseases including vitiligo. IL-35 is one of the newest member of IL-12 cytokine family.

OBJECTIVES

The purpose of our study was to examine serum IL-35 levels in addition to serum IL-12, IL-23, IL-27 levels in the vitiligo patients and control group, and to investigate the relationship of these cytokines with the characteristics of vitiligo.

METHODS

Serum IL-12, IL-23, IL-27 and IL-35 levels of 87 vitiligo patients and 70 healthy volunteers were analyzed using the enzyme-linked immunosorbent assay (ELISA). We compared the IL-12 cytokine family levels in the patient and control groups, and investigated the relationship of these levels with the characteristics of vitiligo.

RESULTS

Patients had higher levels of IL-12 (31.2 versus 20.1, P < 0.001) and IL-35 (9.6 versus 8.1, P = 0.031). Patient and control groups had similar levels of IL-23 (P = 0.78) but were correlated with the Vitiligo Area Scoring Index (VASI) (P = 0.022, r = 0.35). Patients had lower levels of IL-27 (207.6 versus 258.7, P < 0.001). In addition, the levels of serum IL-27 were correlated negatively with the Vitiligo Disease Activity (VIDA), and positively with disease duration (P = 0.007, r = 0.30).

CONCLUSIONS

Differences of serum levels between Vitiligo patients and healthy controls, significant relationships with the characteristics of vitiligo suggest that the IL-12 cytokine family may play a role in the pathogenesis of vitiligo.

STING Protein-Based In Situ Vaccine Synergizes CD4+ T, CD8+ T, and NK Cells for Tumor Eradication

Stimulator of interferon genes (STING) signaling is a promising target in cancer immunotherapy, with many ongoing clinical studies in combination with immune checkpoint blockade (ICB). Existing STING-based therapies largely focus on activating CD8+ T cell or NK cell-mediated cytotoxicity, while the role of CD4+ T cells in STING signaling has yet to be extensively studied in vivo. Here, a distinct CD4-mediated, protein-based combination therapy of STING and ICB as an in situ vaccine, is reported. The treatment eliminates subcutaneous MC38 and YUMM1.7 tumors in 70-100% of mice and protected all cured mice against rechallenge. Mechanistic studies reveal a robust TH 1 polarization and suppression of Treg of CD4+ T cells, followed by an effective collaboration of CD4+ T, CD8+ T, and NK cells to eliminate tumors. Finally, the potential to overcome host STING deficiency by significantly decreasing MC38 tumor burden in STING KO mice is demonstrated, addressing the translational challenge for the 19% of human population with loss-of-function STING variants.

Single-dose injectable nanovaccine-in-hydrogel for robust immunotherapy of large tumors with abscopal effect

Current cancer immunotherapy [e.g., immune checkpoint blockade (ICB)] only benefits small subsets of patients, largely due to immunosuppressive tumor microenvironment (TME). In situ tumor vaccination can reduce TME immunosuppression and thereby improve cancer immunotherapy. Here, we present single-dose injectable (nanovaccines + ICBs)-in-hydrogel (NvIH) for robust immunotherapy of large tumors with abscopal effect. NvIH is thermo-responsive hydrogel co-encapsulated with ICB antibodies and novel polymeric nanoparticles loaded with three immunostimulatory agonists for Toll-like receptors 7/8/9 (TLR7/8/9) and stimulator of interferon genes (STING). Upon in situ tumor vaccination, NvIH undergoes rapid sol-to-gel transformation, prolongs tumor retention, sustains the release of immunotherapeutics, and reduces acute systemic inflammation. In multiple poorly immunogenic tumor models, single-dose NvIH reduces multitier TME immunosuppression, elicits potent TME and systemic innate and adaptive antitumor immunity with memory, and regresses both local (vaccinated) and distant large tumors with abscopal effect, including distant orthotopic glioblastoma. Overall, NvIH holds great potential for tumor immunotherapy.

Pharmacological inhibition of demethylzeylasteral on JAK-STAT signaling ameliorates vitiligo

BACKGROUND

The activation of CD8⁺ T cells and their trafficking to the skin through JAK-STAT signaling play a central role in the development of vitiligo. Thus, targeting this key disease pathway with innovative drugs is an effective strategy for treating vitiligo. Natural products isolated from medicinal herbs are a useful source of novel therapeutics. Demethylzeylasteral (T-96), extracted from Tripterygium wilfordii Hook F, possesses immunosuppressive and anti-inflammatory properties.

METHODS

The efficacy of T-96 was tested in our mouse model of vitiligo, and the numbers of CD8⁺ T cells infiltration and melanocytes remaining in the epidermis were quantified using whole-mount tail staining. Immune regulation of T-96 in CD8⁺ T cells was evaluated using flow cytometry. Pull-down assay, mass spectrum analysis, molecular docking, knockdown and overexpression approaches were utilized to identify the target proteins of T-96 in CD8⁺ T cells and keratinocytes.

RESULTS

Here, we found that T-96 reduced CD8⁺ T cell infiltration in the epidermis using whole-mount tail staining and alleviated the extent of depigmentation to a comparable degree of tofacitinib (Tofa) in our vitiligo mouse model. In vitro, T-96 decreased the proliferation, CD69 membrane expression, and IFN-γ, granzyme B, (GzmB), and perforin (PRF) levels in CD8⁺ T cells isolated from patients with vitiligo. Pull-down assays combined with mass spectrum analysis and molecular docking showed that T-96 interacted with JAK3 in CD8⁺ T cell lysates. Furthermore, T-96 reduced JAK3 and STAT5 phosphorylation following IL-2 treatment. T-96 could not further reduce IFN-γ, GzmB and PRF expression following JAK3 knockdown or inhibit increased immune effectors expression upon JAK3 overexpression. Additionally, T-96 interacted with JAK2 in IFN-γ-stimulated keratinocytes, inhibiting the activation of JAK2, decreasing the total and phosphorylated protein levels of STAT1, and reducing the production and secretion of CXCL9 and CXCL10. T-96 did not significantly inhibit STAT1 and CXCL9/10 expression following JAK2 knockdown, nor did it suppress upregulated STAT1-CXCL9/10 signaling upon JAK2 overexpression. Finally, T-96 reduced the membrane expression of CXCR3, and the culture supernatants pretreated with T-96 under IFN-γ stressed keratinocytes markedly blocked the migration of CXCR3⁺CD8⁺ T cells, similarly to Tofa in vitro.

CONCLUSION

Our findings demonstrated that T-96 might have positive therapeutic responses to vitiligo by pharmacologically inhibiting the effector functions and skin trafficking of CD8⁺ T cells through JAK-STAT signaling.

Dysregulated Th1 cells in lung squamous cell carcinoma

Lung squamous cell carcinoma (LUSC) is a common subtype of lung cancer. Th1 cells contribute to antitumor immune responses. However, there are few studies on Th1 cells in LUSC. CD8⁺ T cells are the main driver of the antitumor immunity, targeting tumor cells killing. Th1 cells play an important auxiliary role in this process. Here, we used single-cell RNA-seq (scRNA-seq) to analyze qualified CD4⁺ T cells and Th1 cells (defined CD4⁺ T cells with 1 or more of STAT1⁺ , STAT4⁺ , T-bet⁺ , and IFN-γ⁺ as Th1 cells) from tissues of 8 LUSC patients. Then, we validated Th1 cells and CD8⁺ T cells of 32 LUSC patients by multiplex immunofluorescence staining and immunohistochemistry. Finally, we used flow cytometry to detect IFN-γ of CD4⁺ T cells in human PBMCs coincubated with LUSC-derived supernatant to simulate a tumor inhibitory microenvironment. ScRNA-seq showed IFN-γ⁺ Th1 cells account for 25.28% of all Th1 cells. Gene ontology and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analyses of differentially expressed genes between IFN-γ⁺ Th1 cells and IFN-γ^- Th1 cells confirmed the decreased IFN-γ is associated with endoplasmic reticulum stress (ER stress). Multiplex immunofluorescence staining and immunohistochemistry proved there was a positive correlation between IFN-γ⁺ STAT1⁺ T-bet⁺ Th1 cells and CD8⁺ T cells. Flow cytometry showed IFN-γ secreted by Th1 cells is decreased. These findings support the claim that Th1 cells' function is suppressed in LUSC. Through scRNA-seq, we found that the decreased Th1 cells' function is associated with ER stress, which requires further study. Overall, these findings may produce a new method for the treatment of LUSC.

Adoptive immunotherapy with transient anti-CD4 treatment enhances anti-tumor response by increasing IL-18Rαhi CD8+ T cells

Adoptive T cell therapy (ACT) requires lymphodepletion preconditioning to eliminate immune-suppressive elements and enable efficient engraftment of adoptively transferred tumor-reactive T cells. As anti-CD4 monoclonal antibody depletes CD4⁺ immune-suppressive cells, the combination of anti-CD4 treatment and ACT has synergistic potential in cancer therapy. Here, we demonstrate a post-ACT conditioning regimen that involves transient anti-CD4 treatment (CD4^post). Using murine melanoma, the combined effect of cyclophosphamide preconditioning (CTX^pre), CD4^post, and ex vivo primed tumor-reactive CD8⁺ T-cell infusion is presented. CTX^pre/CD4^post increases tumor suppression and host survival by accelerating the proliferation and differentiation of ex vivo primed CD8⁺ T cells and endogenous CD8⁺ T cells. Endogenous CD8⁺ T cells enhance effector profile and tumor-reactivity, indicating skewing of the TCR repertoire. Notably, enrichment of polyfunctional IL-18Rα^hi CD8⁺ T cell subset is the key event in CTX^pre/CD4^post-induced tumor suppression. Mechanistically, the anti-tumor effect of IL-18Rα^hi subset is mediated by IL-18 signaling and TCR–MHC I interaction. This study highlights the clinical relevance of CD4^post in ACT and provides insights regarding the immunological nature of anti-CD4 treatment, which enhances anti-tumor response of CD8⁺ T cells.

Lymphodepleting preconditioning is generally required prior to adoptive T cell therapy (ACT). Here the authors show in a preclinical melanoma model that anti-CD4 treatment as a post-conditioning regimen enhances the anti-tumor efficacy of ACT by promoting the expansion of IL-18Rα^hi CD8⁺ T cells.

A case of palmar hypopigmentation induced by capecitabine in a gastrointestinal cancer patient

INTRODUCTION

Capecitabine is an antimetabolite antineoplastic agent widely used in the treatment gastrointestinal cancers. The common frequently reported cutaneous adverse drug reaction associated with capecitabin are a palmar-plantar erythrodysesthesia syndrome, rash and hyperpigmentation. This case reports a capecitabine-induced palmar hypopigmentation.

CASE REPORT

We report the case of a 74-years old patient with jejunum adenocarcinoma treated by capecitabine. The patient developed a pseudo-vitiligo after 2 cycles capecitabine and without history of cutaneous disorders. The skin lesions were characterized with skin hypopigmentation on both hands.Management and outcome: The hypopigmentation slowly recovered after capecitabine discontinuation.

CONCLUSION

This is the first described case of pseudo-vitiligo induced by capecitabine. This impressive but non-severe adverse effect should be known by oncologists and oncology pharmacists to reassure the patients in particular about the possible recovery after discontinuation of capecitabine.

Microbial antigens-loaded myeloma cells enhance Th2 cell proliferation and myeloma clonogenicity via Th2-myeloma cell interaction

Background

Myeloma cells retain B cell functions, considered to be potential antigen presenting cells, yet there is little information regarding promoting Th2 cell proliferation or the direct effects to myeloma on the Th2 cells stimulated by microbial antigens-loaded myeloma cells.

Methods

Mixed lymphocyte reaction was used colorimetric assays via CCK8-kit. Surface molecular expression was performed by flow cytometry, cells sorting using microbeads. The concentrations of cytokines in serum were assessed using an ELISA kit. Clonogenic assay were performed in a methylcellulose culture system. Statistical analysis was assessed using the Student’s t-test or one-way analysis of variance for multiple comparisons test.

Results

The expression of HLA-DR, CD80 and CD40 on RPMI8266 cell membrane surface was upregulated by interaction with interferon-γ and/or Bacillus Calmette-Guerin Vaccine (BCGV). RPMI8266 cells were able to induce the mixed lymphocyte reaction in a dose-dependent fashion. The Th2 ratio induced by RPMI8266 treated by BCGV and interferon-γ (treated-RPMI8266) cells was only slightly greater than by untreated-tumor cells, but the serum IL-4 level secreted by Th2 cells was markedly higher in treated-RPMI8266 cells group. Th2 cells stimulated by treated-myeloma cells could directly promote treated-myeloma cell clonogenicity in a dose-dependent manner. Anti-HLADR IgG2b completely blocked increased of IL-4 secretion by Th2 cells stimulated by treated-myeloma cells, while also blocked enhancing the clonogenicity of treated tumor cells stimulated by MM-Th2 cells.

Conclusions

These results indicate that a novel mechanism of myeloma pathogenesis in myeloma cells could act as an APC to present microbial Ags to Th2 cells, promoting Th2 cell proliferation, consequently facilitating tumor development by close interaction between Th2 myeloma cells. Taken together, the microbial Ag presenting course of MM-Th2-MM interactions—restricted by MHC class-II—may result in tumor development such that all factors involved in the system could have a potential for myeloma therapeutic intervention.

First-in-human phase 1 study of IT1208, a defucosylated humanized anti-CD4 depleting antibody, in patients with advanced solid tumors

Background

Transient CD4⁺ T cell depletion led to the proliferation of tumor-specific CD8⁺ T cells in the draining lymph node and increased infiltration of PD-1⁺CD8⁺ T cells into the tumor, which resulted in strong anti-tumor effects in tumor-bearing mice. This is a first-in-human study of IT1208, a defucosylated humanized anti-CD4 monoclonal antibody, engineered to exert potent antibody-dependent cellular cytotoxicity.

Methods

Patients with advanced solid tumors were treated with intravenous IT1208 at doses of 0.1 or 1.0 mg/kg. The first patient in each cohort received a single administration, and the other patients received two administrations of IT1208 on days 1 and 8.

Results

Eleven patients were enrolled in the 0.1 mg/kg (n = 4) and 1.0 mg/kg cohorts (n = 7). Grade 1 or 2 infusion-related reactions was observed in all patients. Decreased CD4⁺ T cells in peripheral blood due to IT1208 were observed in all patients and especially in those receiving two administrations of 1.0 mg/kg. CD8⁺ T cells increased on day 29 compared with baseline in most patients, resulting in remarkably decreased CD4/8 ratios. One microsatellite-stable colon cancer patient achieved durable partial response showing increased infiltration of both CD4⁺ and CD8⁺ T cells into tumors after IT1208 administration. Moreover, transcriptomic profiling of the liver metastasis of the patient revealed upregulation of the expression of interferon-stimulated genes, T cell activation-related genes, and antigen presentation-related genes after IT1208 administration. Two additional patients with gastric or esophageal cancer achieved stable disease lasting at least 3 months.

Conclusions

IT1208 monotherapy successfully depleted CD4⁺ T cells with a manageable safety profile and encouraging preliminary efficacy signals, which warrants further investigations, especially in combination with immune checkpoint inhibitors.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0677-y) contains supplementary material, which is available to authorized users.

Oncolytic adenovirus coexpressing interleukin-12 and decorin overcomes Treg-mediated immunosuppression inducing potent antitumor effects in a weakly immunogenic tumor model

Interleukin (IL)-12 is a potent antitumor cytokine. However, immunosuppressive tumor microenvironments containing transforming growth factor-β (TGF-β) attenuate cytokine-mediated antitumor immune responses. To enhance the efficacy of IL-12-mediated cancer immunotherapy, decorin (DCN) was explored as an adjuvant for overcoming TGF-β-mediated immunosuppression. We designed and generated a novel oncolytic adenovirus (Ad) coexpressing IL-12 and DCN (RdB/IL12/DCN). RdB/IL12/DCN-treated tumors showed significantly greater levels of interferon (IFN)-γ, tumor necrosis factor-α, monocyte chemoattractant protein-1, and IFN-γ-secreting immune cells than tumors treated with cognate control oncolytic Ad expressing a single therapeutic gene (RdB/DCN or RdB/IL12). Moreover, RdB/IL12/DCN attenuated intratumoral TGF-β expression, which positively correlated with reduction of Treg cells in draining lymph nodes and tumor tissues. Furthermore, tumor tissue treated with RdB/IL12/DCN showed increases infiltration of CD8⁺ T cells and proficient viral spreading within tumor tissues. These results demonstrated that an oncolytic Ad co-expressing IL-12 and DCN induces a potent antitumor immune response via restoration of antitumor immune function in a weakly immunogenic murine 4T1 orthotopic breast cancer model. These findings provide new insights into the therapeutic mechanisms of IL-12 plus DCN, making it a promising cancer immunotherapeutic agent for overcoming tumor-induced immunosuppression.

Targeting macrophage anti-tumor activity to suppress melanoma progression

By phagocytosing cancer cells and their cellular debris, macrophages play a critical role in nonspecific defense (innate immunity) and, as antigen presenters, they help initiate specific defense mechanisms (adaptive immunity). Malignant melanoma is a lethal disease due to its aggressive capacity for metastasis and resistance to therapy. For decades, considerable effort has gone into development of an effective immunotherapy for treatment of metastatic melanoma. In this review, we focus on the anti-tumor activities of macrophages in melanoma and their potential as therapeutic targets in melanoma. Although macrophages can be re-educated through intercellular signaling to promote tumor survival owing to their plasticity, we expect that targeting the anti-tumor activity of macrophages remains a promising strategy for melanoma inhibition. The combination of tumoricidal macrophage activation and other treatments such as surgery, chemotherapy, and radiotherapy, may provide an effective and comprehensive anti-melanoma strategy.

A fully human IgG1 anti-PD-L1 MAb in an in vitro assay enhances antigen-specific T-cell responses

Monoclonal antibodies (MAbs) that interfere with checkpoint molecules are being investigated for the treatment of infectious diseases and cancer, with the aim of enhancing the function of an impaired immune system. Avelumab (MSB0010718C) is a fully human IgG1 MAb targeting programmed death-ligand 1 (PD-L1), which differs from other checkpoint-blocking antibodies in its ability to mediate antibody-dependent cell-mediated cytotoxicity. These studies were conducted to define whether avelumab could enhance the detection of antigen-specific immune response in in vitro assays. Peripheral blood mononuclear cells from 17 healthy donors were stimulated in vitro, with and without avelumab, with peptide pools encoding for cytomegalovirus, Epstein-Barr virus, influenza and tetanus toxin or the negative peptide control encoding for human leukocyte antigen. These studies show for the first time that the addition of avelumab to an antigen-specific IVS assay (a) increased the frequency of activated antigen-specific CD8(+) T lymphocytes, and did so to a greater extent than that seen with commercially available PD-L1-blocking antibodies, (b) reduced CD4(+) T-cell proliferation and (c) induced a switch in the production of Th2 to Th1 cytokines. Moreover, there was an inverse correlation between the enhancement of CD8(+) T-cell activation and reduction in CD4(+) T-cell proliferation induced by avelumab. These findings provide the rationale for the use of avelumab anti-PD-L1 in in vitro assays to monitor patient immune responses to immunotherapies.

Enhancement of antitumor effect by peptide vaccine therapy in combination with anti-CD4 antibody: Study in a murine model

Purpose

The clinical efficacy of cancer peptide vaccine therapy is insufficient. To enhance the anti-tumor effect of peptide vaccine therapy, we combined this therapy with an anti-CD4 mAb (GK1.5), which is known to deplete CD4⁺ cells, including regulatory T cells (Tregs).

Methods

To determine the treatment schedule, the number of lymphocyte subsets in the peripheral blood of mice was traced by flow cytometry after administration of anti-CD4 mAb. The ovalbumin (OVA)_257–264 peptide vaccine was injected intradermally and anti-CD4 mAb was administered intraperitoneally into C57BL/6 mice at different schedules. We evaluated the enhancement of OVA peptide-specific cytotoxic T lymphocyte (CTL) induction in the combination therapy using the ELISPOT assay, CD107a assay, and cytokine assay. We then examined the in vivo metastasis inhibitory effect by OVA peptide vaccine therapy in combination with anti-CD4 mAb against OVA-expressing thymoma (EG7) in a murine liver metastatic model.

Results

We showed that peptide-specific CTL induction was enhanced by the peptide vaccine in combination with anti-CD4 mAb and that the optimized treatment schedule had the strongest induction effect of peptide-specific CTLs using an IFN-γ ELISPOT assay. We also confirmed that the CD107a⁺ cells secreted perforin and granzyme B and the amount of IL-2 and TNF produced by these CTLs increased when the peptide vaccine was combined with anti-CD4 mAb. Furthermore, metastasis was inhibited by peptide vaccines in combination with anti-CD4 mAb compared to peptide vaccine alone in a murine liver metastatic model.

Conclusion

The use of anti-CD4 mAb in combination with the OVA peptide vaccine therapy increased the number of peptide-specific CTLs and showed a higher therapeutic effect against OVA-expressing tumors. The combination with anti-CD4 mAb may provide a new cancer vaccine strategy.

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Peptide-specific CTL induction and function were enhanced by depletion of CD4⁺ cells.

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Anti-tumor effect by the peptide vaccine was enhanced by the depletion of CD4⁺ cells.

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Metastasis was inhibited by vaccine with depletion of CD4⁺ cells in a murine model.

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Combination with the depletion of CD4⁺ cells could be a new cancer vaccine strategy.

Robust Antitumor Effects of Combined Anti-CD4-Depleting Antibody and Anti-PD-1/PD-L1 Immune Checkpoint Antibody Treatment in Mice

Depletion of CD4(+) cells in tumor-bearing mice has strong antitumor effects. However, the mechanisms underlying these effects and the therapeutic benefits of CD4(+) cell depletion relative to other immunotherapies have not been fully evaluated. Here, we investigated the antitumor effects of an anti-CD4-depleting mAb as a monotherapy or in combination with immune checkpoint mAbs. In B16F10, Colon 26, or Lewis lung carcinoma subcutaneous tumor models, administration of the anti-CD4 mAb alone had strong antitumor effects that were superior to those elicited by CD25(+) Treg depletion or other immune checkpoint mAbs, and which were completely reversed by CD8(+) cell depletion. CD4(+) cell depletion led to the proliferation of tumor-specific CD8(+) T cells in the draining lymph node and increased infiltration of PD-1(+)CD8(+) T cells into the tumor, with a shift toward type I immunity within the tumor. Combination treatment with the anti-CD4 mAb and immune checkpoint mAbs, particularly anti-PD-1 or anti-PD-L1 mAbs, synergistically suppressed tumor growth and greatly prolonged survival. To our knowledge, this work represents the first report of robust synergy between anti-CD4 and anti-PD-1 or anti-PD-L1 mAb therapies.

Opening a niche for therapy: local lymphodepletion helps the immune system to fight melanoma

In this issue, Fujiwara et al. report that local ablation of CD4+ T cells in a murine B16 melanoma model, together with concomitant activation of the immune system by OX40L, leads to complete rejection of the melanomas. Rejection was driven mainly by CD8+ T cells, which infiltrated the melanomas and secreted sizeable amounts of IFN-γ. However, CD8+ T-cell infiltration also caused the recruitment of immunosuppressive myeloid-derived suppressor cells (MDSCs). Although these cells did not prevent the rejection of the melanomas, in clinical settings the long-term repopulation of tumors by MDSCs may counteract successful treatment. Thus, local ablation of CD4+ leukocytes may improve anti-melanoma therapies in humans, but at the same time MDSC levels in the tumor cells have to be kept in check to ensure treatment success.

Intratumoral CD4+ T lymphodepletion sensitizes poorly immunogenic melanomas to immunotherapy with an OX40 agonist

Previous studies have shown that the antitumor effects of OX40 agonists depend on the immunogenicity of the tumor and that poorly immunogenic tumors such as B16F10 melanomas do not respond to OX40 agonist treatment. In this study, we have shown that intratumoral CD4+ T lymphodepletion sensitized poorly immunogenic B16F10 melanomas to immunotherapy with an OX40 agonist. CD4+ T lymphodepletion dramatically altered the tumor immune microenvironment, making it more susceptible to the antitumor effects of an OX40 agonist by enhancing the accumulation of CD8+ T cells and natural killer (NK) cells in tumor tissue. However, unexpectedly, the number of CD11b+ Gr-1(+) myeloid-derived suppressor cells (MDSCs) within tumor tissues also significantly increased as a result of CD4+ T lymphodepletion. As a countermeasure against CD8+ T-cell accumulation, CCR2-positive CD11b+ Gr-1(int) (monocytic) MDSCs predominantly increased. Treatment with an OX40 agonist under CD4+ T lymphodepletion neither reduced MDSCs nor increased CD8+ T cells and NK cells, but further enhanced the expression of cytotoxic molecules from tumor-infiltrating effector cells. Our results suggest that combined immunotherapy using both an OX40 agonist and CD4+ T lymphodepletion could be a promising therapeutic strategy for poorly immunogenic tumors and might be more effective if further combined with a therapeutic strategy targeting MDSCs.

Introduction of 65 kDa Antigen ofMycobacterium tuberculosisto Cancer Cells Enhances Anti-Tumor Effect of BCG Therapy

Bacillus Calmette Guerin (BCG) immunotherapy has anti-tumorigenic effects against bladder cancer. To improve the efficacy of BCG therapy, we introduced the gene encoding the 65 kDa heat shock protein (hsp) of Mycobacterium tuberculosis into a mouse malignant melanoma cell line (B16). An expression vector harboring the 65 kDa antigen gene was transfected into B16 using Lipofectamine, then expression of the antigen was confirmed by RT-PCR and Western blotting. Several cell lines expressing 65 kDa antigen were established (B16/65 kDa). We also established a control cell line transfected with the vector alone (B16/con). All cell lines (B16, B16/con, B16/65 kDa) were injected intraperitoneally into syngeneic mice with or without BCG prior immunization and the development of tumor ascites was examined. To analyze the mechanism of the anti-tumor effect, CD4 T cells or CD8 T cells were depleted in vivo by administering the corresponding monoclonal antibody. B16/65k Da expressed the 65 kDa hsp of M. tuberculosis. The tumor growth of B16/65 kDa was slightly retarded in naive mice, but significantly inhibited by BCG. The anti-tumor effect was totally abrogated in mice deficient in CD4 T cells, suggesting that CD4 T cells are involved in this process. The 65 kDa hsp of M. tuberculosis was expressed after gene transduction in a malignant melanoma cell line and significantly enhanced the anti-tumor effect of BCG immunotherapy. CD4 T cells play an important role in this anti-tumor effect.

Enhancement of myeloma development mediated though myeloma cell-Th2 cell interactions after microbial antigen presentation by myeloma cells and DCs

Microbial agents are regarded as a potential cause of tumors, but their direct effects on tumors, such as myeloma, are not well studied. Our studies demonstrated that expression of HLA-DR and CD40 on the myeloma cell membrane surface is upregulated by interferon-γ and/or microbial antigens (Ags). Unlike prior studies, our study showed that Th2 cells cannot promote myeloma growth directly. However, Bacillus Calmette–Guerin Vaccine (BCGV)-specific Th2 cells stimulated by BCGV-loaded dendritic cells (DCs) promoted myeloma clonogenicity directly when the myeloma cells expressed major histocompatibility complex Class-II molecules (MHC-II) and took up BCGV Ag. B-cell lymphoma 6 (Bcl-6) protein expression and the proportion of HLA-DR⁺ or CD40⁺ cells were higher in colonies of Th2 cell-stimulated myeloma cells. Furthermore, anti-HLA-DR or neutralizing CD40 antibody could prevent this increase in Bcl-6 expression and colony number. These results indicate that microbes and microbial Ag-specific Th2 cells may directly impact the biology of myeloma and contribute to tumor progression. Activation may be limited to MHC-II⁺ myeloma cells that retain B cell and stem cell characteristics. Taken together, our data suggest that factors involved in microbial Ag presentation, such as DCs, Th2 cells and so on, are potential targets for myeloma therapeutic intervention.

Transient depletion of CD4(+) T cells augments IL-21-based immunotherapy of disseminated neuroblastoma in syngeneic mice

IL-21 is a member of the IL-2 cytokine family, produced by CD4+ T cells. We previously showed that immunotherapy (IT) with IL-21-transduced neuroblastoma cells (Neuro2a/IL-21) cured 33% of syngeneic mice bearing systemic NB. Here, we studied whether the removal of Treg cells could potentiate the therapeutic efficacy of Neuro2a/IL-21 vaccine. The administration of anti-CD25 mAb, which targets Treg cells, slightly potentiated the effect of vaccine IT (50% cure rate), but anti-CD4 mAb had a more potent effect leading to 80% cure rate. Anti-CD25 mAb, indeed, only partially depleted CD4+CD25+FoxP3+ Treg cells, whereas anti-CD4 mAb was more effective in this respect, leading to 90% depletion of Treg cells. In mice receiving vaccine+anti-CD4 mAb, which developed systemic immunity to NB, CD4+ T cells counts completely recovered in 90 days. Depletion of CD8+ T cells abrogated the effect of the combined IT, indicating a predominant role of these cells in driving the immune response. In addition, CD8+ T cells from cured mice coinjected with Neuro2a/parental cells (pc) in NOD-SCID mice completely inhibited tumor growth. Spleen cells from mice receiving Neuro2a/IL-21 vaccination showed increased expression of IFN-alpha2, -beta1 and -gamma mRNA. Moreover, mice receiving vaccine therapy alone or vaccine+anti-CD4 mAb showed increased IFN-gamma serum levels and IFN-gamma-producing CD8+ T cells were found in spleen cells. In conclusion, anti-CD4 mAb potentiated IL-21-based IT by removing Treg cells and/or their precursors and other potentially immune-suppressive CD4+ cell subsets, thus allowing the development of an IL-21-driven CD8+ T cell response, which mediates NB rejection.

A reactive ortho-quinone generated by tyrosinase-catalyzed oxidation of the skin depigmenting agent monobenzone: self-coupling and thiol-conjugation reactions and possible implications for melanocyte toxicity

Monobenzone (hydroquinone monobenzylether, 1) is a potent skin depigmenting agent that causes irreversible loss of epidermal melanocytes by way of a tyrosinase-dependent mechanism so far little understood. Herein, we show that 1 can be oxidized by mushroom tyrosinase to an unstable o-quinone (1-quinone) that has been characterized by comparison of its properties with those of a synthetic sample obtained by o-iodoxybenzoic acid-mediated oxidation of 1. Preparative scale oxidation of 1 with tyrosinase and catalytic l-DOPA, followed by reductive workup and acetylation, led to the isolation of two main products that were identified as the acetylated catechol derivative 4 and an unusual biphenyl-type dimer of 4, acetylated 5, arising evidently by coupling of 4 with 1-quinone. In the presence of l-cysteine or N-acetyl-l-cysteine, formation of 4 and 5 was inhibited, and the reaction led instead to monoadducts (6 or 9) and diadducts (7 and 8). A similar behavior was observed when the tyrosinase-promoted oxidation of 1 was carried out in the presence of sulfhydryl-containing peptides, such as reduced glutathione, or proteins, such as bovine serum albumin (BSA), as inferred by detection of adduct 9 by high pressure liquid chromatography-electrochemical detection (HPLC-ED) after acid hydrolysis. The generation and reaction chemistry of 1-quinone described in this article may bear relevance to the etiopathogenetic mechanisms of monobenzone-induced leukoderma as well as to the recently proposed haptenation hypothesis of vitiligo, a disabling pigmentary disorder characterized by irreversible melanocyte loss.

Association of thymic stromal lymphopoietin gene -847C>T polymorphism in generalized vitiligo

Thymic stromal lymphopoietin (TSLP) induces naïve CD4+ T cells to produce Th2 cytokines. In addition, to low production of Th2 cytokines, strong Th1 response, which plays an important role in vitiligo development, has been induced by blockade of TSLP or TSLP receptor. This study examined whether a functional TSLP polymorphism was associated with vitiligo. One hundred and sixty Korean patients with vitiligo and 568 healthy Korean individuals were examined for the four SNPs of TSLP gene. Luciferase activity was measured for promoter assay. The genotype and allele frequencies of -847C>T polymorphism were lower in vitiligo patients compared with the controls, whereas those of wild type were higher (P = 0.004, P = 0.017 respectively). None the less, the promoter activity of -847C decreased significantly (P = 0.013) compared with -847T, expecting lower TSLP mRNA levels in the polymorphism. Collectively, C allele at the TSLP -847C>T polymorphism may increase susceptibility to generalized vitiligo through decreasing TSLP mRNA expression levels.

Expression of interleukins-23 and 27 leads to successful gene therapy of hepatocellular carcinoma

IL-23 and IL-27 are two novel IL-12 cytokine family members who are quite similar to, but yet clearly distinct from IL-12 in their structures and T-cell stimulatory mechanisms. Here, we demonstrated that either IL-27 or IL-23 has potent antitumor activity in murine models of MM45T.Li hepatocellular carcinoma (HCC). These potent antitumor effects were induced primarily by CD8(+)T cells, secreting IFN-gamma while CD4(+)T cells were also involved as a help of antitumor immunity. However, the antitumor response induced by IL-27 was observed from an early stage of tumor growth whereas that of IL-23 was only evident in the late stage of tumor cell proliferation. IL-23 could induce mice to develop a long-term systemic immunologic memory response against parental MM45T.Li tumors cells, an effect IL-27 was not able to accomplish. CTLs specific for MM45T.Li cells were significantly induced by IL-23, whereas antitumor efficacy mediated by IL-27 and IL-12 involved NK cells, which IL-23 failed to activate. Furthermore, we demonstrated that CD40 expression also plays an important role in the induction of antitumor activities by IL-27, IL-23 or IL-12. Together our data suggest that IL-27 and IL-23 may be two novel and attractive candidate agents to apply to cancer immunotherapy.

Roles of idiotype-specific t cells in myeloma cell growth and survival: Th1 and CTL cells are tumoricidal while Th2 cells promote tumor growth

Idiotype (Id) protein, secreted by myeloma cells, is a tumor-specific antigen. Id-based immunotherapy has been explored in patients with myeloma, and results were disappointing. Although previous studies have shown that Id-specific CTLs are able to lyse myeloma cells, it is unclear whether other types of Id-specific T cells, such as type-1 T-helper (Th1) and type-2 T-helper (Th2) cells, are also able to suppress or kill myeloma cells. Using a 5T murine myeloma model, we generated T-cell clones of different subsets and examined their function in the context of myeloma cells. Id-specific CTLs specifically lysed myeloma cells via MHC class I, perforin, and Fas ligand (FasL), and Th1, but not Th2, cells lysed the myeloma cells by FasL-Fas interaction. CTL and Th1 cells also suppressed the growth and function of myeloma cells, whereas Th2 cells promoted the proliferation and enhanced the secretion of Id protein and cytokines by myeloma cells. CTL and Th1, but not Th2, cells were able to eradicate established myeloma in vivo after adoptive transfer. These results show that Id-specific CTL and Th1 are promising effector cells, whereas Th2 provide no protection and may even promote tumor progression in vivo.

Possible mechanisms in the induction of vitiligo-like hypopigmentation by topical imiquimod

The pathogenesis of vitiligo was examined for clues to the pigmentary changes that may occur after treatment with topical imiquimod. The literature varies on the pigmentary changes induced by topical use of imiquimod. The US Food and Drugs Administration lists 68 reports of pigmentary changes out of a total of 1257 reports related to imiquimod lodged from 1997 to 2003. Some studies describe vitiligo-like hypopigmentation associated with imiquimod treatment of genital warts (as with the patient described in this report), molluscum contagiosum, basal cell carcinoma, extramammary Paget's disease and murine melanoma. Other studies report hyperpigmentation associated with imiquimod. The possible mechanisms of hypopigmentation associated with imiquimod treatment are discussed, including antibodies found in sera of patients with vitiligo to nonpigment cell antigens, cytoplasmic pigment cell antigens and pigment cell-surface antigens; stimulation by imiquimod of both the innate immune response and cell-mediated adaptive immunity; and increased sensitivity of melanocytes to oxidative stress. The vitiligo-like hypopigmentation following topical imiquimod treatment is in line with the mode of action of this drug.

Interleukin-12: biological properties and clinical application

Interleukin-12 (IL-12) is a heterodimeric protein, first recovered from EBV-transformed B cell lines. It is a multifunctional cytokine, the properties of which bridge innate and adaptive immunity, acting as a key regulator of cell-mediated immune responses through the induction of T helper 1 differentiation. By promoting IFN-gamma production, proliferation, and cytolytic activity of natural killer and T cells, IL-12 induces cellular immunity. In addition, IL-12 induces an antiangiogenic program mediated by IFN-gamma-inducible genes and by lymphocyte-endothelial cell cross-talk. The immunomodulating and antiangiogenic functions of IL-12 have provided the rationale for exploiting this cytokine as an anticancer agent. In contrast with the significant antitumor and antimetastatic activity of IL-12, documented in several preclinical studies, clinical trials with IL-12, used as a single agent, or as a vaccine adjuvant, have shown limited efficacy in most instances. More effective application of this cytokine, and of newly identified IL-12 family members (IL-23 and IL-27), should be evaluated as therapeutic agents with considerable potential in cancer patients.

Vitiligo puzzle: the pieces fall in place

Over the years, the role of biochemical, immunological, genetic, and other biological aspects in the pathogenesis of vitiligo has been studied. So far, no convincing model describing the interplay of these contributing factors has been formulated. Based on existing research, we propose that vitiligo has a multi-factorial etiology, characterized by multiple steps, but always involving an increase of external or internal phenol/catechol concentration, serving as a preferred surrogate substrate of tyrosinase, competing with its physiological substrate tyrosine. The conversion of these substrates into reactive quinones is reinforced by a disturbed redox balance (increasing hydrogen peroxide). Such reactive quinones can be covalently bound to the catalytic centre of tyrosinase (haptenation). This could give rise to a new antigen, carried by Langerhans cells to the regional lymph node, stimulating the proliferation of cytotoxic T cells. However, the activation of such cytotoxic cells is only a first step in skin melanocyte killing, which also depends on a shift in the balance between immune defence and tolerance, e.g. resulting from a decrease in properly functioning T-regulatory cells. With this new model, based on a synthesis of several of the existing theories, in mind, the external and internal factors involved in the etiopathogenesis of vitiligo are reviewed, against the background of reported clinical data, experimental studies and existing and potential new therapies. A similar complex mechanism may also lead to some other autoimmune diseases.

Treatment of vitiligo vulgaris with narrow-band UVB and oral Polypodium leucotomos extract: a randomized double-blind placebo-controlled study

BACKGROUND

The first choice treatment for vitiligo vulgaris is narrow-band UVB (NB-UVB), but no satisfactory treatment exists.

OBJECTIVES

To investigate if Polypodium leucotomos, an antioxidative and immunomodulatory plant extract, improves NB-UVB-induced repigmentation.

METHODS

Fifty patients with vitiligo vulgaris randomly received 250 mg oral P. leucotomos or placebo three times daily, combined with NB-UVB twice weekly for 25-26 weeks.

RESULTS

Repigmentation was higher in the P. leucotomos group vs. placebo in the head and neck area (44% vs. 27%, P = 0.06). Small repigmentation increases (P = n.s.) were observed for the trunk (6% increased repigmentation), extremities (4%), and hands and feet (5%) in the P. leucotomos group vs. placebo. Patients attending more than 80% of required NB-UVB sessions showed increased repigmentation in the head and neck area in the P. leucotomos group vs. placebo (50% vs. 19%, P < 0.002); no significant differences were seen in the other body areas. Patients with skin types 2 and 3 showed more repigmentation in the head and neck area in the P. leucotomos group vs. placebo (47% vs. 21%, P = 0.01), and no significant differences were seen in the other body areas. No conclusions could be drawn on skin types 4 and 5 due to low patient numbers.

CONCLUSION

There is a clear trend towards an increase in repigmentation of vitiligo vulgaris affecting the head and neck area when NB-UVB phototherapy is combined with oral P. leucotomos. This effect may be more pronounced in light skin types.

Interleukin-23 and interleukin-27 exert quite different antitumor and vaccine effects on poorly immunogenic melanoma

Recent studies revealed that two novel interleukin (IL)-12-related cytokines, IL-23 and IL-27, have potent antitumor activities. However, the antitumor effects were mainly evaluated in relatively highly immunogenic tumors and have not been fully evaluated against nonimmunogenic or poorly immunogenic tumors. In this study, we investigated the antitumor efficacies of IL-23 and IL-27 on poorly immunogenic B16F10 melanoma and found that the antitumor responses mediated by IL-23 and IL-27 were clearly different. In syngeneic mice, mouse single-chain (sc) IL-23-transfected B16F10 (B16/IL-23) tumors exhibited almost the same growth curve as B16F10 parental tumor about until day 20 after tumor injection and then showed growth inhibition or even regression. In contrast, scIL-27-transfected B16F10 (B16/IL-27) tumors exhibited significant retardation of tumor growth from the early stage. In vivo depletion assay revealed that the antitumor effect of B16/IL-23 was mainly mediated by CD8+ T cells and IFN-gamma whereas that of B16/IL-27 mainly involved natural killer cells and was independent of IFN-gamma. We also found that antitumor effects of B16/IL-23 and B16/IL-27 were synergistically enhanced by treatment with IL-18 and IL-12, respectively. Furthermore, B16/IL-23-vaccinated mice developed protective immunity against parental B16F10 tumors but B16/IL-27-vaccinated mice did not. When combined with prior in vivo depletion of CD25+ T cells, 80% of B16/IL-23-vaccinated mice completely rejected subsequent tumor challenge. Finally, we showed that the systemic administration of neither IL-23 nor IL-27 induced such intense toxicity as IL-12. Our data support that IL-23 and IL-27 might play a role in future cytokine-based immunotherapy against poorly immunogenic tumors.

Induction of cellular immunity against hair follicle melanocyte causes alopecia

Alopecia areata (AA) is generally regarded as an organ-specific autoimmune disease. Although it has been hypothesized that the autoimmunity is mediated by T cells and that hair follicle melanocyte is one of the targets, definitive evidence is lacking. We here demonstrate that AA-like lesions can be induced in mice by inducing CD8(+) T-cell-mediated immunity to hair follicle melanocytes. We found that hair loss was induced in mice-bearing interleukin-12-producing B16 melanoma cells by the depletion of CD4(+) T cells, accompanied by vitiligo-like coat color change. The alopecic lesions varied in size from pachy to extensive. In many instances, hair loss developed and was followed by the regrowth of white hairs. Histological analysis revealed that mononuclear cells infiltrated in and around the bulb region of hair follicles. Furthermore, immunohistochemical examination clearly showed the intra-follicular infiltration of CD8(+) T cells. Neither the vitiligo-like coat color nor AA-like lesions were induced when CD8(+) T cells were codepleted. These observations indicate that the induction of CD8(+) T-cell-mediated immunity against hair follicle melanocytes causes alopecia. It is thought that there are many types of AA with different mechanisms, targets etc. Although hair follicle melanocytes have long been thought to be one of the targets of AA, evidence to support the hypothesis is sparse. Therefore, we believe that our observation is significant to support the hypothesis.

Vaccine with beta-defensin 2-transduced leukemic cells activates innate and adaptive immunity to elicit potent antileukemia responses

Murine beta-defensin 2 (MBD2) is a small antimicrobial peptide of the innate immune system. Recent study showed that MBD2 could not only recruit immature dendritic cells but also activate them by Toll-like receptor 4 and thus may provide a critical link between the innate immune system and the adaptive immune response. In this report, we examined the antileukemia activity of MBD2 in a murine model of acute lymphoid leukemia (ALL) L1210. L1210 cells were engineered to secrete biologically functional MBD2. MBD2-modified L1210 (L1210-MBD2) showed significantly reduced leukemogenecity, resulting in a 80% rate of complete leukemia rejection. Inoculation of mice with L1210-MBD2 induced enhanced CTL and natural killer (NK) activity and augmented interleukin-12 and IFN-gamma production. All the recovered mice from the inoculation showed a protective immunity to the following challenge with parental L1210 cells and generate leukemia-specific memory CTL. Vaccines with irradiated L1210-MBD2 cells could cure 50% leukemia-bearing mice. Depletion of CD8+ T cells but not CD4+ T cells completely abrogated the antileukemia activity of MBD2. Interestingly, NK cells were also required for the MBD2-mediated antileukemia response, although ALL generally display a high degree of resistance to NK-mediated lysis. Our results suggest that MBD2 can activate both innate and adaptive immunity to generate potent antileukemia response, and MBD2 immunotherapy warrants further evaluation as a potential treatment for ALL.

Unraveling the complex relationship between cancer immunity and autoimmunity: lessons from melanoma and vitiligo

A relationship between melanoma and vitiligo, a skin disorder characterized by the loss of melanocytes, has been postulated for many decades. In some cases, vitiligo is almost certainly a manifestation of autoimmune-mediated destruction of melanocytes. Melanocytes and melanoma cells share melanocyte differentiation antigens. Based on a number of observations, de novo vitiligo developing in patients with melanoma has been regarded as a sign of good prognosis. The immune system tolerates or ignores differentiation antigens because these antigens are self-derived. Therefore, immune tolerance or ignorance must be overcome to prime naive T and B cells to induce cancer immunity and autoimmunity against melanocyte differentiation antigens. Mouse models of concurrent melanoma and autoimmune vitiligo have revealed strategies to overcome immune ignorance or tolerance to melanocyte differentiation antigens: immunization with self-antigens as altered self (e.g., orthologues or mutated versions), expression in viral vectors, passive immunization with antibodies or T cells, incorporating potent adjuvants into active immunization, and blockade or removal of a downregulatory mechanism. Extensive investigations into the mechanisms that lead to tumor immunity and autoimmunity elicited by certain differentiation antigens have further revealed a variety of distinct cellular and molecular requirements, which are redundant and alternative.

Tumor-induced suppression of interferon-γ production and enhancement of interleukin-10 production by natural killer (NK) cells: paralleled to CD4+ T cells

The predominance of type two cytokines in syngeneic B16 tumor-bearing mice was confirmed by analysing supernatant contents and mRNA copies of IFN-gamma, IL-4, IL-5, IL-10 and IL-13 from splenocytes. The cytokine-producing lymphocytes were then examined by double-staining flowcytometry. Both CD4+IFN-gamma+ T cells and DX5+IFN-gamma+ NK cells from spleen significantly declined, interestingly, the declining degrees of DX5+IFN-gamma+ NK cells were much greater than those of CD4+IFN-gamma+ T cells by the percentage in whole NK or T cells or the absolute amounts per spleen at early tumor stage (day 10) or tumor-advanced stage (day 20). In contrast to DX5+IFN-gamma+ NK cells, DX5+IL-10+ NK cells increased during tumor progression, the increasing degrees of DX5+IL-10+ NK cells were also much greater than those of CD4+IL-10+ T cells by the percentage or the absolute amounts. Though the percentage of DX5+IL-4+ NK cells only increased in early tumor stage (day 10), the increasing degree was also greater than that of CD4+IL-4+ T cells. In 20xfield view under laser confocal microscope, the mean numbers of DX5+IFN-gamma+ NK cells and CD4+IFN-gamma+ T cells dramatically declined after tumor inoculation. These results suggest that cytokines produced by NK cells, at least partly, account for the balance of type one and two cytokines as done by T cells, and in some conditions, that the NK1 or NK2 cells were possibly more sensitive to tumor progression.

CpG stimulation of precursor B-lineage acute lymphoblastic leukemia induces a distinct change in costimulatory molecule expression and shifts allogeneic T cells toward a Th1 response

Immunostimulatory DNA containing unmethylated cytosine-phosphate-guanosine (CpG) induces the development of T helper 1 (Th1) immune responses. The response of B cells to CpG stimulation involves increased proliferation, cytokine production, and costimulatory molecule expression. Similar effects have been observed following CpG stimulation of a variety of malignant B cells. Pediatric precursor B acute lymphoblastic leukemia (B-ALL) cells express low levels of costimulatory molecules and are generally poor stimulators of T-cell responses. In this study, we evaluated the impact of CpG stimulation on precursor B-ALL cell lines and pediatric patient-derived samples. The ability to respond to CpG oligodeoxynucleotides was determined by the level of Toll-like receptor 9 (TLR9) expression. In contrast to both nonleukemic B-cell precursors and mature B cells, the response of precursor B-ALL cells was characterized by increased CD40 expression but only small changes in CD86 levels and no induction of CD80 expression. CpG stimulation of ALL blasts produced increased levels of interleukin-6 (IL-6), IL-8, and IL-10 but no detectable IL-12p70 and led to a skewing of allogeneic T cells, with enhanced interferon gamma (IFN-gamma) production and reduced secretion of IL-5. These results demonstrate the functional relevance of CpG stimulation of precursor B-ALL cells and provide a rational basis for study of these agents for use in treatment of this disease.

Effect of renal cell carcinomas on the development of type 1 T-cell responses

PURPOSE

We reported that in renal cell carcinoma patients with active disease, T-cell reactions to the tumor-associated antigens MAGE-6 and EphA2 are highly skewed toward TH2-type cytokine responses [interleukin (IL) 5]. Herein, we determined whether tumor-derived products, including gangliosides isolated from renal cell carcinoma patients, participate in the down-regulation of type 1 T-cell responses.

EXPERIMENTAL DESIGN

T cells from healthy volunteers or renal cell carcinoma patients were cultured in the presence and absence of supernatants derived from renal cell carcinoma explants or with gangliosides isolated from those tumor supernatants. T cells were stimulated or not with either autologous dendritic cells pulsed with superantigen (Staphylococcus enterotoxin B) or with phorbol 12-myristate 13-acetate and ionomycin and then were assessed for type 1 or type 2 responses (cytokine production and gene expression) and apoptosis.

RESULTS

Tumor supernatants efficiently inhibited the TH1-type responses [interferon (IFN) gamma] of T cells stimulated with either S. enterotoxin B or phorbol 12-myristate 13-acetate and ionomycin but had no inhibitory effect on activated T-cell production of type 2 cytokines (IL-4, IL-5, and IL-10). Likewise, IFN-gamma mRNA and protein production were inhibited when T cells were cocultured with either renal cell carcinoma supernatant-derived gangliosides or a commercial source of purified GD1a. It was also determined that gangliosides impair type 1 responses by inducing apoptosis of activated T cells.

CONCLUSIONS

We propose that renal cell carcinoma-derived tumor products such as gangliosides can induce a type 2 bias in antitumor immunity by initiating apoptosis in the IFN-gamma-producing type 1 effector cells. This represents a relevant mechanism by which renal cell carcinoma can inhibit protective antitumor immunity.

In vivo elimination of CD25+ regulatory T cells leads to tumor rejection of B16F10 melanoma, when combined with interleukin-12 gene transfer

CD4(+)CD25(+) T cells are an important population that plays a crucial role in the maintenance of peripheral self-tolerance. Recently, it was shown that the elimination of these cells by in vivo administration of anti-CD25 monoclonal antibody (mAb) caused the regression of highly immunogenic tumors in syngeneic mice. In this study, we examined whether B16F10 melanoma cells regressed with the elimination of CD25(+) regulatory T cells. We found the melanoma cells were not affected at all by in vivo anti-CD25 mAb administration alone but tumor rejection resulted in all mice when the administration was combined with IL-12 gene transfer to tumor cells. In vivo, depletion of natural killer (NK) cells or CD8(+) T cells cancelled the tumor rejection. NK-cell depletion allowed IL-12-transfected B16F10 melanoma (B16/IL-12) to grow from an early stage and resulted in a more rapid tumor growth of B16/IL-12 than that in mice without administration of anti-CD25 mAb. On the other hand, CD8(+) T-cell depletion did not affect the tumor growth in the early phase but allowed B16/IL-12 to grow in rather a late phase and resulted in almost the same degree of tumor growth as in mice without administration of anti-CD25 mAb. In a previous study, we showed that the elimination of CD4(+) T cells enhanced the antitumor effect of B16/IL-12 and induced vitiligo-like coat color alteration. Therefore, we also examined the frequency of the change to a vitiligo-like coat color in mice showing tumor rejection caused by CD25(+) T-cell elimination to compare with the mechanism enhancing the antitumor effects by cell elimination. The elimination of CD25(+) T cells did not induce vitiligo-like coat color changes, though that of CD4(+) T cells induced the change in 60% of mice. Furthermore, we confirmed that elimination of CD25(+) T cells did not affect the T-helper (Th) 1/Th2 cytokine profile, while that of CD4(+)T cells abrogated the Th2 cytokines (IL-4 and IL-10) and resulted in a Th1-dominant cytokine profile in the tumor-draining lymph nodes (TDLNs) of B16/IL-12-bearing mice. These results indicate that in vivo depletion of CD25(+) regulatory T cells is a potent useful adjuvant in immunotherapy of B16F10 melanoma, when combined with IL-12 gene transfer and that the enhancement of the antitumor effect by CD25(+) T-cell depletion is mediated through CD8(+) T cells and may differ from the enhancing mechanism caused by CD4(+) T-cell depletion.

Therapeutic HER2/Neu DNA Vaccine Inhibits Mouse Tumor Naturally Overexpressing Endogenous Neu

The therapeutic efficacy of HER2/c-erbB-2/neu DNA immunization on mouse tumor cells expressing exogenous human or rat p185neu but not on mouse tumor cells naturally expressing mouse p185neu has been demonstrated. We investigated the feasibility of using N-terminal rat neu DNA immunization on mouse tumor overexpressing endogenous p185neu and enhancing the therapeutic efficacy of this vaccine by fusion to various cytokine genes, including interleukin-2 (IL-2), interleukin-4 (IL-4), or granulocyte-macrophage colony-stimulating factor. In a therapeutic model, N'-neu-IL-2 DNA vaccine was significantly better than N'-neu DNA vaccine, and N'-neu DNA vaccine was significantly better than control DNA or N'-neu-IL-4 DNA vaccine. The therapeutic efficacy of DNA vaccines was correlated with tumor infiltration of CD8+ T cells. Depletion of CD8+ T cells completely abolished the therapeutic effects of N'-neu-IL-2 DNA vaccine and N'-neu DNA vaccine. Depletion of CD4+ T cells after tumor implantation had no influence on N'-neu-IL-2 DNA vaccine, but enhanced the therapeutic efficacy of N'-neu DNA vaccine. Our results demonstrate that rat N'-neu DNA vaccine has a therapeutic effect on established tumor through the CD8+ T-cell-dependent pathway. Depletion of CD4+ T cells or fusion to the IL-2 gene can thus further enhance the therapeutic effects of N'-neu DNA immunization on mouse tumor expressing endogenous p185neu.

Suppression of hepatocellular carcinoma growth via oral immune regulation towards tumor-associated antigens is associated with increased NKT and CD8+ lymphocytes

BACKGROUND

Oral immune regulation towards viral proteins was previously shown to modulate the anti-HBV immune response. Adoptive transfer of orally immunomodulated lymphocytes suppressed the growth of hepatocellular carcinoma (HCC) expressing HBsAg in athymic mice. NKT lymphocytes play a role in the defense against tumor growth.

AIM

To evaluate the effect of oral immune regulation towards HCC-associated antigens or HBV proteins on growth of HBsAg-expressing HCC, and to determine the role of NKT lymphocytes in immune modulation.

METHODS

Sublethally irradiated athymic Balb/c mice were injected with 10(7) human hepatoma cells followed 10 days later by transplantation of 2 x 10(6) splenocytes from naive donor mice. Immune modulation was performed via feeding of HCC-extracted proteins or HBV antigens (HBsAg + Pre S1 + Pre S2). The control group was fed with bovine serum albumin (BSA). Mice were followed for survival, tumor volume, and serum alpha-fetoprotein levels. To determine the role of NKT cells in tumor suppression, cytokine expression and FACS analysis for CD4+, CD8+, and NK1.1+ T lymphocyte subsets were performed.

RESULTS

Oral immune regulation towards HCC-extracted proteins induced complete tumor suppression in recipient mice. Mortality rates were 0% in HCC-immune-regulated mice, compared with an 80% mortality rate using HBV antigens and a 100% mortality rate in control mice. Oral immune regulation towards HCC prevented weight loss. No visible tumor mass was observed in orally immune-regulated mice as compared with 112 mm(3) in controls. Serum alphaFP levels were 0.9, 378 and 1,358 ng/ml in HCC, HBV immune-regulated and controls, respectively. Immune regulation towards HCC antigens significantly increased the NK1.1+ T lymphocytes/CD4+ and CD8+/CD4+ ratios. IFNgamma production increased two-fold.

CONCLUSION

Oral immune regulation towards HCC antigens effectively enhanced the anti-tumor immune response, thus suppressing the growth of HCC in mice. This effect was associated with an increased NKT,CD8+/CD4+ lymphocyte ratio and may be mediated via enhancement of IFNgamma production.

Spontaneous vitiligo in an animal model for human melanoma: role of tumor-specific CD8+ T cells

Tumor antigen-reactive T cells can be detected in a large proportion of melanoma patients, but their efficacy on tumor control in vivo remains unclear. On the other hand, vitiligo, a skin disorder characterized by patchy depigmented macules, may occur spontaneously or after antitumor therapies. Moreover, vitiligo is significantly associated with positive clinical response, but the mechanism is not understood. Therefore, the establishment of a relevant animal model in which melanoma and vitiligo spontaneously develop stepwise may be useful for better understanding of the parameters involved in the destruction of both benign and malignant melanocytes. In a previous work, we established a mouse model for melanoma in which MT/ret transgenic mice express the ret oncogene fused to the metallothionein promoter. Here we report that melanoma leads to spontaneous vitiligo. We further investigate, for the first time in this model, the natural antitumor T-cell response and evaluate the role of cellular immunity in the development of the disease. Interestingly, the occurrence of spontaneous tumor nodules in MT/ret mice with melanoma-associated vitiligo is significantly delayed when compared in melanoma mice without vitiligo. Moreover, a significant proportion of mice with melanoma-associated vitiligo resisted a challenge with syngeneic melanoma cells in contrast to animals without vitiligo. Our results confirm that vitiligo is associated with clinical benefit and further demonstrate the crucial role of CD8+ T cells for tumor control in melanoma-associated vitiligo.

NK and CD8+ T cell-mediated eradication of poorly immunogenic B16-F10 melanoma by the combined action of IL-12 gene therapy and 4-1BB costimulation

In previous reports, systemic administration of a stimulatory monoclonal antibody directed against the 4-1BB receptor had no effect on survival or tumor burden in mice inoculated with the poorly immunogenic B16-F10 melanoma. We combined IL-12 gene transfer with 4-1BB costimulation to explore a previously noted cooperative anti-tumor effect against this model tumor. We hypothesize that the innate immune response mediated by IL-12-activated natural killer (NK) cells initiates the activation of the immune system, leading to the priming of T cells, whereas 4-1BB costimulation enhances the function of primed tumor-specific T cells. The effect of the combination therapy on the growth of subcutaneous (s.c.) tumors and pulmonary metastasis was examined. The combination therapy significantly retarded the growth of subcutaneously-inoculated tumors, and 50% of tumor-bearing mice survived with complete tumor regression. In contrast, neither IL-12 gene transfer nor anti-4-1BB antibody administration alone was as effective. Enhanced CTL activity against both B16-F10 tumor cells and TRP-2-pulsed EL4 syngeneic tumor cells was observed in tumor-bearing animals treated with the combination therapy 2 weeks after treatment and, in long-term survivors from this combination therapy, at >120 days. In a pulmonary metastatic model, only the combination therapy generated significant protection against metastasis. In vivo depletion of NK or CD8(+) but not CD4(+) subsets eliminated the protective immunity. Furthermore, NK cell depletion significantly reduced both tumor-specific CTL activity and the number of tumor-specific IFN-gamma-producing cells, suggesting that this synergistic effect requires the participation of both NK and CD8(+) T cells.

Altered patterns of T cell cytokine production induced by relapsed pre-B ALL cells

Relapse of pediatric acute lymphoblastic leukemia (ALL) remains a significant clinical problem. The graft-versus-leukemia (GVL) effect after hematopoietic stem cell transplantation indicates that immune mechanisms may play a role in the control of ALL blasts. In this study, we analyzed primary diagnostic and relapsed pre-B ALL samples for the surface expression of several molecules implicated in immune responses and for the induction of allogeneic T cell responses. There were no significant differences in the expression of CD11a, CD40, CD80 and CD86 or MHC classes I and II molecules between the diagnostic and relapsed samples. We found no significant differences in the overall ability of diagnostic and relapsed pre-B ALL samples to induce T cell proliferation and cytokine production. However, in the case of T cell responses induced by diagnostic ALL samples, there was excellent correlation between proliferation and production of all cytokines analyzed. In the case of relapsed samples, the only correlation obtained was with IL-5. This observation indicates that the nature of the immune response generated by relapsed ALL cells in an allogeneic setting differs from that obtained with diagnostic samples, suggests a biasing towards a Th2 response may contribute to the evasion of effective immune responses by relapsed ALL.

CD4+/CD25+ Regulatory Cells Inhibit Activation of Tumor-Primed CD4+ T Cells with IFN-γ-Dependent Antiangiogenic Activity, as well as Long-Lasting Tumor Immunity Elicited by Peptide Vaccination

CD25(+) regulatory T (T reg) cells suppress the activation/proliferation of other CD4(+) or CD8(+) T cells in vitro. Also, down-regulation of CD25(+) T reg cells enhance antitumor immune responses. In this study, we show that depletion of CD25(+) T reg cells allows the host to induce both CD4(+) and CD8(+) antitumoral responses following tumor challenge. Simultaneous depletion of CD25(+) and CD8(+) cells, as well as adoptive transfer experiments, revealed that tumor-specific CD4(+) T cells, which emerged in the absence of CD25(+) T reg cells, were able to reject CT26 colon cancer cells, a MHC class II-negative tumor. The antitumoral effect mediated by CD4(+) T cells was dependent on IFN-gamma production, which exerted a potent antiangiogenic activity. The capacity of the host to mount this antitumor response is lost once the number of CD25(+) T reg cells is restored over time. However, CD25(+) T reg cell depletion before immunization with AH1 (a cytotoxic T cell determinant from CT26 tumor cells) permits the induction of a long-lasting antitumoral immune response, not observed if immunization is conducted in the presence of regulatory cells. A study of the effect of different levels of depletion of CD25(+) T reg cells before immunization with the peptide AH1 alone, or in combination with a Th determinant, unraveled that Th cells play an important role in overcoming the suppressive effect of CD25(+) T reg on the induction of long-lasting cellular immune responses.

Protective Effects of a Protein-Bound Polysaccharide, PSK, Against Candida albicans Infection in Syngeneic Tumor-Bearing Mice via Th1 Cell Functions

We investigated the effects of a protein-bound polysaccharide, PSK, on the resistance of tumor-bearing mice against Candida albicans infection. In BALB/c mice that had received subcutaneous (sc) transplantation of fibrosarcoma Meth A, viable fungal counts were increased in the kidney and the mean survival period was shortened after challenge with C. albicans, compared with healthy mice. Oral administration of PSK to such mice resulted in a significant decrease of viable fungal counts and a prolongation of the mean survival period. The ratio of CD4-positive T cells in the spleen was decreased in noninfected tumor-bearing mice and the decrease was prevented by PSK, although in vitro anticandida activities of phagocytes were not significantly affected by tumor burden or PSK. Further, intracellular interferon (IFN)-gamma productivity was enhanced and the number of IFN-gamma-producing CD4-positive T cells was enhanced by PSK. PSK enhanced the gene expression of interleukin (IL)-12 and IFN-gamma in the spleen of tumor-bearing mice inoculated with C. albicans. Treatments with anti-IL-12 or anti-IFN-gamma antibody reduced the anti-infectious effects of PSK. These findings suggest that the protective effect of PSK on sublethal inoculation with C. albicans in tumor-bearing mice is possibly mediated by Th1 cell functions.

IL-21 activates both innate and adaptive immunity to generate potent antitumor responses that require perforin but are independent of IFN-gamma

IL-21 is a key factor in the transition between innate and adaptive immune responses. We have used the cytokine gene therapy approach to study the antitumor responses mediated by IL-21 in the B16F1 melanoma and MethA fibrosarcoma tumor models in mice. Retrovirally transduced tumor cells secreting biologically functional IL-21 have growth patterns in vitro similar to that of control green fluorescent protein-transduced cells, but are completely rejected in vivo. We show that IL-21 activates NK and CD8(+) T cells in vivo, thus mediating complete rejection of poorly immunogenic tumors. Rejection of IL-21-secreting tumors requires the presence of cognate IL-21R and does not depend on CD4(+) T cell help. Interestingly, perforin, but not IFN-gamma or other major Th1 and Th2 cytokines (IL-12, IL-4, or IL-10), is required for the IL-21-mediated antitumor response. Moreover, IL-21 results in 50% protection and 70% cure of nonimmunogenic tumors when given before and after tumor challenge, respectively, in C57BL/6 mice. We conclude that IL-21 immunotherapy warrants clinical evaluation as a potential treatment for cancer.

Epidemiology of vitiligo and associated autoimmune diseases in Caucasian probands and their families

Generalized vitiligo is an autoimmune disorder characterized by acquired white patches of skin and overlying hair, the result of loss of melanocytes from involved areas. The most common disorder of pigmentation, vitiligo occurs with a frequency of 0.1-2.0% in various populations. Family clustering of cases is not uncommon, in a non-Mendelian pattern suggestive of multifactorial, polygenic inheritance. We surveyed 2624 vitiligo probands from North America and the UK regarding clinical characteristics, familial involvement, and association with other autoimmune disorders, the largest such survey ever performed. More than 83% of probands were Caucasians, and the frequency of vitiligo appeared approximately equal in males and females. The frequency of vitiligo in probands' siblings was 6.1%, about 18 times the population frequency, suggesting a major genetic component in disease pathogenesis. Nevertheless, the concordance of vitiligo in monozygotic twins was only 23%, indicating that a non-genetic component also plays an important role. Probands with earlier disease onset tended to have more relatives affected with vitiligo, suggesting a greater genetic component in early onset families. The frequencies of six autoimmune disorders were significantly elevated in vitiligo probands and their first-degree relatives: vitiligo itself, autoimmune thyroid disease (particularly hypothyroidism), pernicious anaemia, Addison's disease, systemic lupus erythematosus, and probably inflammatory bowel disease. These associations indicate that vitiligo shares common genetic aetiologic links with these other autoimmune disorders. These results suggest that genomic analysis of families with generalized vitiligo and this specific constellation of associated autoimmune disorders will be important to identify the mechanisms of genetic susceptibility to autoimmunity.

A combination of plasmid DNAs encoding murine fetal liver kinase 1 extracellular domain, murine interleukin-12, and murine interferon-gamma inducible protein-10 leads to tumor regression and survival in melanoma-bearing mice

The vascular endothelial growth factor (VEGF) and its interaction with the vascular endothelial growth factor receptor 2 [VEGFR2/murine fetal liver kinase 1 (Flk-1), human kinase domain receptor] are an important angiogenic pathway leading to tumor vascularization. A plasmid DNA encoding the complete extracellular domain (ECD) of murine Flk-1 including the endogenous signal sequence was designed as a possible competitor of the receptor to sequester VEGF. The plasmid DNA was used to treat B16F10 cell-induced subcutaneous melanomas in syngeneic mice. The Flk-1 ECD-encoding plasmid DNA injected intramuscularly did not lead to tumor reduction. However, intratumoral injection caused a dose-dependent reduction and significant retardation of tumor growth. Blood vessels analyzed by immunohistochemistry with anti-CD31 antibodies as indicators of vascularization appeared smaller in diameter after treatment. A combination of Flk-1 ECD and DNA encoding murine interleukin-12 or murine interferon-gamma inducible protein-10 improved the effect, leading to tumor regression and long-term survival of the mice.

CD4+ Th2 cell recognition of HLA-DR-restricted epitopes derived from CAMEL: a tumor antigen translated in an alternative open reading frame

Tumor Ag NY-ESO-1 is an attractive target for immunotherapy of cancer, since both CD8(+) CTL and CD4(+) Th cells against NY-ESO-1 have been described. Moreover, NY-ESO-1 as well as the highly homologous tumor Ag LAGE-1 are broadly expressed in various tumor types. Interestingly, the NY-ESO-1 and LAGE-1 genes also encode for proteins translated in an alternative open reading frame. These alternatively translated NY-ESO-ORF2 and CAMEL proteins, derived from the NY-ESO-1 and LAGE-1 genes, respectively, have been demonstrated to be immunogenic, since CTL specific for these proteins have been isolated from melanoma patients. In this study a panel of advanced melanoma patients was screened for the presence of Th cells specific for the alternatively translated tumor Ags NY-ESO-ORF2 and CAMEL. PBMC of melanoma patients were stimulated for 4 days with mixes of overlapping peptides covering the entire NY-ESO-ORF2 and CAMEL protein sequences and were tested for the release of type 1 (IFN-gamma) and type 2 (IL-13) cytokines in ELISPOT assays. In three of 15 patients, T cells specific for two CAMEL peptides (CAMEL(71-92) and CAMEL(81-102)) could be detected. From one of these patients, CD4(+) T cell clones specific for CAMEL(81-102) could be generated. These clones recognized a naturally processed epitope presented in both HLA-DR11 and HLA-DR12 and produced high levels of IL-4, IL-5, and IL-13. In conclusion, this study shows the presence of Th cells specific for the alternatively translated tumor Ag CAMEL in melanoma patients and is the first report that describes the isolation of tumor Ag-specific CD4(+) Th 2 clones.