Immature, Semi-Mature, and Fully Mature Dendritic Cells: Toward a DC-Cancer Cells Interface That Augments Anticancer Immunity

Melanoma targeting with the loco-regional chemotherapeutic, Melphalan: From cell death to immunotherapeutic efficacy

All immunoregulatory chemotherapeutics are chiefly applied in a systemic setting for anticancer therapy. However, immune responses following loco-regional application of chemotherapy may differ from those after systemic application. We recently found that Melphalan, a prototypical loco-regionally applied chemotherapeutic agent, exhibits the ability to increase the immunogenicity of dying melanoma cells.

Effects of 3-dimensional culture conditions (collagen-chitosan nano-scaffolds) on maturation of dendritic cells and their capacity to interact with T-lymphocytes

In the body, there is a natural three-dimensional (3D) microenvironment in which immune cells, including dendritic cells (DC), play their functions. This study evaluated the impact of using collagen-chitosan 3D nano-scaffolds in comparisons to routine 2D culture plates on DC phenotype and functions. Bone marrow-derived DC were cultured on scaffolds and plates and then stimulated with lipopolysaccharide (LPS) or chitosan-based nanoparticles (NP) for 24 h. Thereafter, DC viability, expression of maturation markers and levels of cytokines secretion were evaluated. In another set of studies, the DC were co-cultured with allogenic T-lymphocytes in both the 2D and 3D systems and effects on DC-induction of T-lymphocyte proliferation and cytokine release were analyzed. The results indicated that CD40, CD86 and MHC II marker expression and interleukin (IL)-12, IL-6 and tumor necrosis factor (TNF)-α secretion by DC were enhanced in 3D cultures in comparison to by cells maintained in the 2D states. The data also showed that DNA/chitosan NP activated DC more than LPS in the 3D system. T-Lymphocyte proliferation was induced to a greater extent by DNA/NP-treated DC when both cell types were maintained on the scaffolds. Interestingly, while DC induction of T-lymphocyte interferon (IFN)-γ and IL-4 release was enhanced in the 3D system (relative to controls), there was a suppression of transforming growth factor (TGF)-β production; effects on IL-10 secretion were variable. The results here suggested that collagen-chitosan scaffolds could provide a pro-inflammatory and activator environment to perform studies to analyze effects of exogenous agents on the induction of DC maturation, NP uptake and/or cytokines release, as well as for the ability of these cells to potentially interact with other immune system cells in vitro.

Antitumor immunity triggered by melphalan is potentiated by melanoma cell surface-associated calreticulin

Systemic chemotherapy generally has been considered immunosuppressive, but it has become evident that certain chemotherapeutic drugs elicit immunogenic danger signals in dying cancer cells that can incite protective antitumor immunity. In this study, we investigated whether locoregionally applied therapies, such as melphalan, used in limb perfusion for melanoma (Mel-ILP) produce related immunogenic effects. In human melanoma biopsies, Mel-ILP treatment upregulated IL1B, IL8, and IL6 associated with their release in patients' locoregional sera. Although induction of apoptosis in melanoma cells by melphalan in vitro did not elicit threshold levels of endoplasmic reticulum and reactive oxygen species stress associated with danger signals, such as induction of cell-surface calreticulin, prophylactic immunization and T-cell depletion experiments showed that melphalan administration in vivo could stimulate a CD8(+) T cell-dependent protective antitumor response. Interestingly, the vaccination effect was potentiated in combination with exogenous calreticulin, but not tumor necrosis factor, a cytokine often combined with Mel-ILP. Our results illustrate how melphalan triggers inflammatory cell death that can be leveraged by immunomodulators such as the danger signal calreticulin.

Lactic acid bacteria strains exert immunostimulatory effect on H. pylori-induced dendritic cells

The aim of this study was to find out if selected lactic acid bacteria (LAB) strains (antagonistic or nonantagonistic against H. pylori in vitro) would differ in their abilities to modulate the DCs maturation profiles reflected by their phenotype and cytokine expression patterns. Methods. Monocyte-derived DCs maturation was elicited by their direct exposure to the LAB strains of L. rhamnosus 900 or L. paracasei 915 (antagonistic and nonantagonistic to H. pylori, resp.), in the presence or absence of H. pylori strain cagA+. The DCs maturation profile was assessed on the basis of surface markers expression and cytokines production. Results. We observed that the LAB strains and the mixtures of LAB with H. pylori are able to induce mature DCs. At the same time, the L. paracasei 915 leads to high IL-10/IL-12p70 cytokine ratio, in contrast to L. rhamnosus 900. Conclusions. This study showed that the analyzed lactobacilli strains are more potent stimulators of DC maturation than H. pylori. Interestingly from the two chosen LAB strains the antagonistic to H. pylori-L. rhamnosus strain 900 has more proinflammatory and probably antibactericidal properties.

Assessing the Effects of Concurrent versus Sequential Cisplatin/Radiotherapy on Immune Status in Lung Tumor-Bearing C57BL/6 Mice

Concurrent and sequential cisplatin-based chemoradiotherapy regimens are standard therapeutic approaches in cancer treatment. Recent clinical data suggest that these different dosing schedules may adversely affect antigen-specific immunotherapy. The goal of the present preclinical study was to explore the effects of concurrent and sequential cisplatin/radiotherapy on immune status in a lung cancer mouse model. A total of 150 C57BL/6 mice were randomized into six treatment groups: control; 8 Gy thoracic radiotherapy (dose schedules 1 and 2); cisplatin 2.5 mg/kg i.p.; cisplatin + radiotherapy (concurrent); and cisplatin + radiotherapy (sequential; n = 25, all groups). At the end of the study (week 41), serum cytokines were assessed by multiplex immunoassay, surface markers of spleen-derived lymphocytes were assessed by immunostaining and flow cytometry, lung tumor expression of programmed death ligands 1 and 2 (PD-L1/2) was evaluated by immunohistochemistry, and miRNA profiling was performed in serum and lymphocytes by quantitative real-time PCR. Lung whole mounts were prepared to assess treatment effects on lung tumor foci formation. The results showed that sequential chemoradiotherapy (two cycles of cisplatin followed by 8 Gy radiotherapy) had equivalent antitumor activity as concurrent therapy. However, sequential cisplatin/radiotherapy resulted in significant differences in several immune response biomarkers, including regulatory T cells, miR-29c, expression of costimulatory molecule CD28, and serum IFNγ. PD-L1 and PD-L2 were strongly expressed in tumor foci, but no trend was seen between groups. These results suggest that monitoring immune status may be necessary when designing treatment regimens combining immunotherapy with chemoradiotherapy.

Complex metastatic niches: already a target for therapy?

Metastatic spread is an inefficient process which requires generation of supportive microenvironments in which cancer cells can survive, proliferate and escape from immune attack. These niches are induced by systemic and locally produced factors and establish a tumor-supportive and immune suppressive environment which is molecularly and functionally different from the niche at the primary site. Tumor dormancy may result if the niche is not sufficiently supportive/protective. Co-evolution of cancer cells and the surrounding microenvironment creates a large number of such dynamic niches, and we are just beginning to elucidate the complexity of these interactions and their tissue-specific differences. We will discuss exciting possibilities but also challenges which are immanent when trying to target these stromal responses for diagnosis and therapy.

Dual therapeutic benefit of electroporation-mediated DNA vaccination in vivo: Enhanced gene transfer and adjuvant activity

DNA vaccination consists of administering an antigen-coding nucleotide sequence. In order to improve the efficacy of DNA vaccines, electroporation is one of the most commonly used methods to enhance DNA uptake. Here, we discuss additional immunological effects of electroporation that are key aspects for inducing immunity in response to DNA vaccines.

Cancer Vaccines in the World of Immune Suppressive Monocytes (CD14(+)HLA-DR(lo/neg) Cells): The Gateway to Improved Responses

Dendritic cells are an important target in cancer immunotherapy based on their critical role in antigen presentation and response to tumor development. The capacity of dendritic cells to stimulate anti-tumor immunity has led investigators to use these cells to mediate anti-tumor responses in a number of clinical trials. However, these trials have had mixed results. The typical method for generation of ex vivo dendritic cells starts with the purification of CD14(+) cells. Our studies identified a deficiency in the ability to generate mature dendritic cell using CD14(+) cells from cancer patients that corresponded with an increased population of monocytes with altered surface marker expression (CD14(+)HLA-DR(lo/neg)). Further studies identified systemic immune suppression and increased concentrations of CD14(+)HLA-DR(lo/neg) monocytes capable of inhibiting T-cell proliferation and DC maturation. Together, these findings strongly suggest that protocols aimed at immune stimulation via monocytes/dendritic cells, if optimized on normal monocytes or in systems without these suppressive monocytes, are unlikely to engender effective DC maturation in vitro or efficiently trigger DC maturation in vivo. This highlights the importance of developing optimal protocols for stimulating DCs in the context of significantly altered monocyte phenotypes often seen in cancer patients.

ER stress, autophagy and immunogenic cell death in photodynamic therapy-induced anti-cancer immune responses

Tumours are a form of pseudo-organs with their own microenvironment where the cancer cells nurture a dysfunctional immune environment incapable of inciting anti-tumour immunity. It had been proposed that the only way to counteract such an immune system dysfunction in tumours is by eliciting, therapeutically, a cancer cell death pathway that is accompanied by high immunogenicity and possibly inhibits or reduces the influence of the pro-tumourigenic cytokine signalling. Subsequently, a small and a large-scale screening study as well as several targeted studies found that few, selected anticancer therapeutic regimens are able to induce a promising kind of cancer cell demise called immunogenic cell death (ICD), which can activate the immune system owing to the spatiotemporally defined emission of danger signals. Recently, photodynamic therapy (PDT) utilizing the photosensitiser, hypericin (Hyp), became the first PDT paradigm characterized to be capable of inducing bona fide ICD. In the present perspective, we discuss the various technical, conceptual, and molecular advancements and unprecedented results revealed by Hyp-PDT that have influenced the fields of ICD, ER stress biology, cancer cell death, anti-cancer immune responses, photoimmunology and PDT.