Efficient Stimulation of T Cell Responses by Human IFN-α–induced Dendritic Cells Does Not Require Toll-like Receptor Triggering

Transcriptome Analysis Shows That IFN-I Treatment and Concurrent SAV3 Infection Enriches MHC-I Antigen Processing and Presentation Pathways in Atlantic Salmon-Derived Macrophage/Dendritic Cells

Type I interferons (IFNs) have been shown to play an important role in shaping adaptive immune responses in addition to their antiviral properties in immune cells. To gain insight into the impact of IFN-I-induced pathways involved in early adaptive immune responses, i.e., antigen-presenting pathways, in an Atlantic salmon-derived (Salmo salar L.) macrophage cell line (TO-cells), we used a comparative de novo transcriptome analysis where cells were treated with IFN-I or kept untreated and concurrently infected with salmonid alphavirus subtype 3 (SAV3). We found that concurrent treatment of TO-cells with IFN-I and SAV3 infection (SAV3/IFN⁺) significantly enriched the major histocompatibility complex class I (MHC-I) pathway unlike the non-IFN-I treated TO-cells (SAV3/IFN⁻) that had lower expression levels of MHC-I pathway-related genes. Genes such as the proteasomal activator (PA28) and β-2 microglobulin (β2M) were only differentially expressed in the SAV3/IFN⁺ cells and not in the SAV3/IFN⁻ cells. MHC-I pathway genes like heat shock protein 90 (Hsp90), transporter of antigen associated proteins (TAPs) and tapasin had higher expression levels in the SAV3/IFN⁺ cells than in the SAV3/IFN⁻ cells. There were no MHC-II pathway-related genes upregulated in SAV3/IFN⁺-treated cells, and cathepsin S linked to the degradation of endosomal antigens in the MHC-II pathway was downregulated in the SAV3/IFN⁻ cells. Overall, our findings show that concurrent IFN-I treatment of TO-cells and SAV3 infection enriched gene expression linked to the MHC-I antigen presentation pathway. Data presented indicate a role of type I IFNs in strengthening antigen processing and presentation that may facilitate activation particularly of CD8+ T-cell responses following SAV3 infection, while SAV3 infection alone downplayed MHC-II pathways.

Different maturation cocktails provide dendritic cells with different chemoattractive properties

Background

Dendritic cells (DC) are currently implemented as immunotherapeutic strategy for the treatment of tumor patients based on their central role in the immune system. Despite good results were obtained in vitro and in animal models, their clinical use has provided limited success suggesting the requirement to optimise the protocol for their production.

Methods

A cDNA array was performed on FastDC obtained from the differentiation of human peripheral blood monocytes stimulated with the clinical gold standard or with two alternative maturation cocktails combining interferon (IFN)γ and ligands for different toll like receptors (TLR).

Results

A stronger modulation of the DC transcriptome with respect to immature DC was found in alternatively stimulated DC when compared to DC stimulated with the clinical gold standard. A major class of molecules differentially expressed using distinct DC stimulation protocols were chemokines. Validation of their differential expression pattern at the mRNA and protein level confirmed the secretion of inflammatory chemokines by the alternative DC. Functional analyses of the chemotactic properties of DC “wash out” supernatants highlighted the ability of alternative, but not of gold standard DC to efficiently recruit immune cells with a prevalence of monocytes. Effector cells belonging to the innate as well as adaptive immunity were also attracted and the interaction with alternative DC resulted in enhanced secretion of IFNγ and induction of cytotoxic activity. Using leukocytes from cancer patients, it was demonstrated that the monocyte-attracting activity targeted cells with an inflammatory phenotype characterised by high levels of HLA-DR expression.

Conclusions

Despite other classes of immune modulatory genes differently expressed in the alternative DC require to be investigated and characterised regarding their functional consequences, the reduced maturation state and chemoattractive properties of the gold standard versus alternative DC clearly promote the necessity to change the clinically used maturation cocktail of DC in order to improve the outcome of patients treated with DC-based vaccines.

Intratumoral injection of IFN-alpha dendritic cells after dacarbazine activates anti-tumor immunity: results from a phase I trial in advanced melanoma

Background

Advanced melanoma patients have an extremely poor long term prognosis and are in strong need of new therapies. The recently developed targeted therapies have resulted in a marked antitumor effect, but most responses are partial and some degree of toxicity remain the major concerns.

Dendritic cells play a key role in the activation of the immune system and have been typically used as ex vivo antigen-loaded cell drugs for cancer immunotherapy.

Another approach consists in intratumoral injection of unloaded DCs that can exploit the uptake of a wider array of tumor-specific and individual unique antigens. However, intratumoral immunization requires DCs endowed at the same time with properties typically belonging to both immature and mature DCs (i.e. antigen uptake and T cell priming). DCs generated in presence of interferon-alpha (IFN-DCs), due to their features of partially mature DCs, capable of efficiently up-taking, processing and cross-presenting antigens to T cells, could successfully carry out this task. Combining intratumoral immunization with tumor-destructing therapies can induce antigen release in situ, facilitating the injected DCs in triggering an antitumor immune response.

Methods

We tested in a phase I clinical study in advanced melanoma a chemo-immunotherapy approach based on unloaded IFN-DCs injected intratumorally one day after administration of dacarbazine. Primary endpoint of the study was treatment safety and tolerability. Secondary endpoints were immune and clinical responses of patients.

Results

Six patients were enrolled, and only three completed the treatment. The chemo-immunotherapy was well tolerated with no major side effects. Three patients showed temporary disease stabilization and two of them showed induction of T cells specific for tyrosinase, NY-ESO-1 and gp100. Of interest, one patient showing a remarkable long-term disease stabilization kept showing presence of tyrosinase specific T cells in PBMC and high infiltration of memory T cells in the tumor lesion at 21 months.

Conclusion

We tested a chemo-immunotherapeutic approach based on IFN-DCs injected intratumorally one day after DTIC in advanced melanoma. The treatment was well tolerated, and clinical and immunological responses, including development of vitiligo, were observed, therefore warranting additional clinical studies aimed at evaluating efficacy of this approach.

Trial registration

Trial Registration Number not publicly available due to EudraCT regulations: https://www.clinicaltrialsregister.eu/doc/EU_CTR_FAQ.pdf

Role of type I interferon in inducing a protective immune response: perspectives for clinical applications

Type I IFNs (IFN-I) are antiviral cytokines endowed with many biological effects, including antitumor activity. Over the last 15 years, an ensemble of studies has revealed that these cytokines play a crucial role in the induction of a protective antitumor immune response. Early in vivo studies in mouse models have been instrumental for understanding the IFN-I-induced host-mediated mechanisms. IFN-α is currently recognized as a powerful inducer of the differentiation/activation of dendritic cells (DCs) and today IFN-α-conditioned DCs represent promising DC candidates for the development of therapeutic cancer vaccines. Moreover, data from pilot clinical trials support the concept of using IFN-α as an enhancer of the response of patients to cancer vaccines. Notably, endogenous IFN-I production does also play a critical role in the antitumor response to some chemotherapeutic agents. Thus, we can now envisage new strategies of clinical use of IFN-α, based on the injection of IFN-conditioned cells as well as the usage of these cytokines as cancer vaccine adjuvants, alone or in combination with other treatments (including epigenetic drugs) to induce an immunogenic cell death and a long lasting antitumor response.

Type I interferons as regulators of human antigen presenting cell functions

Type I interferons (IFNs) are pleiotropic cytokines, initially described for their antiviral activity. These cytokines exhibit a long record of clinical use in patients with some types of cancer, viral infections and chronic inflammatory diseases. It is now well established that IFN action mostly relies on their ability to modulate host innate and adaptive immune responses. Work in recent years has begun to elucidate the mechanisms by which type I IFNs modify the immune response, and this is now recognized to be due to effects on multiple cell types, including monocytes, dendritic cells (DCs), NK cells, T and B lymphocytes. An ensemble of results from both animal models and in vitro studies emphasized the key role of type I IFNs in the development and function of DCs, suggesting the existence of a natural alliance between these cytokines and DCs in linking innate to adaptive immunity. The identification of IFN signatures in DCs and their dysregulation under pathological conditions will therefore be pivotal to decipher the complexity of this DC-IFN interaction and to better exploit the therapeutic potential of these cells.

MAGE-A10 cancer/testis antigen is highly expressed in high-grade non-muscle-invasive bladder carcinomas

Bladder cancer is a common urinary malignancy and a prevalent cause of cancer-related death. Current therapies of early stage non-muscle-invasive bladder cancer (NMIBC) are frequently associated with undesirable toxicities and recurrence. Active antigen-specific immunotherapy may provide a valid therapeutic option for patients with NMIBC. Cancer-testis antigens (CTA) expressed in various tumour types and in a limited range of healthy tissues may represent potential targets for specific immunotherapy. MAGE-A10 is probably the most immunogenic antigen of the MAGE-A family. We evaluated the expression of MAGE-A10 in NMIBC. Seventy-nine patients undergoing surgical treatment for NMIBC were enrolled in the study. MAGE-A10 gene expression was assessed by quantitative real-time polymerase chain reaction. Immunohistochemistry was performed on paraffin-embedded sections. MAGE-A10 gene was specifically expressed in one-third of NMIBC (n = 24: 32.43%). Gene expression was correlated with high tumour grade. MAGE-A10 protein was exclusively detectable in nuclei of tumour cells. More importantly, MAGE-A10 protein was also more frequently detectable in high-grade tumours (p = 0.0001) and in stage T1 tumours invading subepithelial tissue or lamina propria (p = 0.01). A strong correlation between MAGE-A10 staining score and tumour grade and stage could accordingly be observed. These data indicate that MAGE-A10 expression is a feature of aggressive NMIBC and might be used as a novel target for specific immunotherapy of these cancers.

Interferon-α in the generation of monocyte-derived dendritic cells: recent advances and implications for dermatology

Dendritic cells (DCs) have a critical role in antiviral responses, in autoimmune disease pathogenesis and in initiating and maintaining inflammatory skin disorders, and are candidates for cell-based immunotherapeutic approaches for tumours. Recent studies have shown the important role of type I interferons (IFNs) in DC differentiation and activation. In the presence of IFN-α and granulocyte/macrophage colony-stimulating factor monocytes differentiate into DCs referred to as IFN-DCs. In vitro generated IFN-DCs show a partially mature phenotype, are effective in taking up antigens, share features of myeloid DCs, plasmacytoid DCs and natural killer cells, exhibit an enhanced chemotactic response and are capable of migrating to the lymph nodes. IFN-DCs produce several chemokines and cytokines, including T-helper 1 (Th1) mediators belonging to the interleukin-12 family. IFN-DCs stimulate T- and B-cell responses and the production of IFN-γ in mixed lymphocyte reactions and have a capacity to produce IFN-γ themselves. IFN-DCs express several toll-like receptor (TLR) subtypes and TLR ligand stimulation improves their costimulatory molecule expression, increases their Th1 cytokine production and enhances their capacity to stimulate naive T-cell proliferation. Here we review the interaction of IFN-α and monocytes and the role of IFN-DCs in infections, in autoimmunity, in inflammation and in cancer immunotherapy focusing on dermatological conditions.

MAGE-A10 is a nuclear protein frequently expressed in high percentages of tumor cells in lung, skin and urothelial malignancies

MAGE-A10 is a highly immunogenic member of the MAGE-A family of cancer/testis tumor-associated antigens (C/T TAAs). Studies performed with broadly reactive antibodies have helped to initially characterize this TAA. However, no specific reagents have been developed so far, thus preventing a thorough analysis of its expression in healthy and tumoral tissues. We have produced MAGE-A10 gene product in soluble recombinant form, and we have used it to generate specific monoclonal antibodies (mAbs). One of these reagents, recognizing an epitope located at the COOH terminus of the MAGE-A10 gene product, was used to stain a multitumor tissue microarray comprising more than 2,500 paraffin-embedded specimens including healthy tissues, benign tumors and malignancies of different histological origin. MAGE-A10 protein was identified as an intranuclear protein of an apparent molecular weight of 70 kDa, expressed in normal spermatogonia and spermatocytes but in no other healthy tissue. Most importantly, this C/T TAA appears to be expressed in high (>50%) percentages of cancer cells from a number of malignancies, including lung, skin and urothelial tumors. Unexpectedly, high expression of MAGE-A10 TAA at the protein level was also detectable in gynecological malignancies and stomach and gall bladder cancers. The characterization of MAGE-A10-specific reagents might set the stage for the development of targeted active immunotherapy by clarifying potential indications and by allowing the selection of patients eligible for treatment and the monitoring of its effectiveness.

Frequent calcium oscillations lead to NFAT activation in human immature dendritic cells

Spontaneous Ca(2+) oscillations have been observed in a number of excitable and non-excitable cells, but in most cases their biological role remains elusive. In the present study we demonstrate that spontaneous Ca(2+) oscillations occur in immature human monocyte-derived dendritic cells but not in dendritic cells stimulated to undergo maturation with lipopolysaccharide or other toll like-receptor agonists. We investigated the mechanism and role of spontaneous Ca(2+) oscillations in immature dendritic cells and found that they are mediated by the inositol 1,4,5-trisphosphate receptor as they were blocked by pretreatment of cells with the inositol 1,4,5-trisphosphate receptor antagonist Xestospongin C and 2-aminoethoxydiphenylborate. A component of the Ca(2+) signal is also due to influx from the extracellular environment and may be involved in maintaining the level of the intracellular Ca(2+) stores. As to their biological role, our results indicate that they are intimately linked to the "immature" phenotype and are associated with the translocation of the transcription factor NFAT into the nucleus. In fact, once the Ca(2+) oscillations are blocked with 2-aminoethoxydiphenylborate or by treating the cells with lipopolysaccharide, NFAT remains cytoplasmic. The results presented in this report provide novel insights into the physiology of monocyte-derived dendritic cells and into the mechanisms involved in maintaining the cells in the immature stage.