Evaluation of 3 clinical dendritic cell maturation protocols containing lipopolysaccharide and interferon-gamma

Lactobacilli Probiotics Modulate Antibacterial Response Gene Transcription of Dendritic Cells Challenged with LPS

Probiotics are beneficial bacteria that may modulate the immune response by altering the maturation and function of antigen-presenting cells, such as dendritic cells. This study aimed to evaluate the antibacterial gene expression of dendritic cells challenged with LPS and probiotics. Immature dendritic cells were obtained from human CD14+ monocytes and challenged with E. coli LPS and probiotics Lacticaseibacillus rhamnosus (LR-32) and Lactobacillus acidophilus (LA-5) at a ratio DC:bacteria of 1:10. The analysis of gene expression was performed by RT-qPCR using the Kit RT2 human antibacterial response. In the supernatant, the cytokines secretion was determined by ELISA. Tukey post-ANOVA with p at 5% was used for statistical analysis. LPS showed the higher upregulation of 29 genes compared with the groups where probiotics were added to LPS, including genes related to an inflammatory response like BIRC3, CASP1, CCL5, CXCL1, IL12B, IL18, MYD88, NLRP3, RIPK1, and TIRAP. Similarly, LPS increased the transcription of genes enrolled with apoptosis such as CARD6, CASP1, IRF5, MAP2K1, MAP2K4, MAPK1, MYD88, NLRP3, RIPK2, TNF, TNFRSF1A, and XIAP when compared to probiotics groups (p < 0.05). Although probiotics decrease several genes upregulated by LPS, the transcription of encoded cytokines IL12A, IL12B, IL1B, IL6, CXCL8, and TNF genes was maintained upregulated by probiotics, except for IL18, which was downregulated by LA-5. LA-5 led to a higher transcription of IL1B, IL6, and CXCL-8 which was followed by the secretion of these proteins by ELISA. The results suggest that probiotics attenuate the transcription of inflammatory and immune response genes caused by LPS.

Targeting endoplasmic reticulum associated degradation pathway combined with radiotherapy enhances the immunogenicity of esophageal cancer cells

Immunogenic cell death (ICD) is essential for the activation of immune system against cancer. We aimed to investigate the efficacy of endoplasmic reticulum (ER)-associated protein degradation (ERAD) inhibitors (EerI and NMS-873) in enhancing radiation-induced ICD in esophageal cancer (EC). EC cells were administered with ERAD inhibitors, radiation therapy (RT), and the combination treatment. ICD hallmarks including calreticulin (CALR), adenosine triphosphate (ATP), and high mobility group protein B1 (HMGB1) were detected. The efficacy of ERAD inhibitors combined with RT in stimulating ICD was analyzed. Additionally, the role of ICD hallmarks in immune cell infiltration and patient survival was investigated. Inhibiting ERAD pathways was able to stimulate ICD component emission from dying EC cells in a dose-dependent pattern. Radiation-induced ICD was significantly increased after high doses RT (≥10 Gy). ERAD inhibitor combined with moderate dose RT (≥6 Gy) was capable of stimulating increased ICD in EC cells. Dual therapy could elicit the antitumor immune response by enhancing dendritic cells maturation and phagocytosis. Further investigation revealed a significant correlation between CALR and tumor-infiltrating immune cells. Low expression of ATP and HMGB1 and high expression of CALR were associated with favorable survival in patients with EC. The immunogenicityof EC can be enhanced by ERAD inhibitors combined with moderate doses of RT. ICD hallmark genes, especially CALR, are correlated to immune cell infiltration and clinical outcomes in EC. The present results demonstrated an important method to improve the immunogenicity of EC cells for enhanced antitumor immune response.

Sitagliptin Induces Tolerogenic Human Dendritic Cells

Sitagliptin, an anti-diabetic drug, is a dipeptidyl peptidase (DPP)-4/CD26 inhibitor with additional anti-inflammatory and immunomodulatory properties. In this study, we investigated for the first time the effect of sitagliptin on the differentiation and functions of human dendritic cells generated from monocytes (MoDCs) for 4 days using the standard GM-CSF/IL-4 procedure. LPS/IFN-γ treatment for an additional 24 h was used for maturation induction of MoDCs. Sitagliptin was added at the highest non-cytotoxic concentration (500 µg/mL) either at the beginning (sita 0d protocol) or after MoDC differentiation (sita 4d protocol). Sitagliptin impaired differentiation and maturation of MoDCs as judged with the lower expression of CD40, CD83, CD86, NLRP3, and HLA-DR, retention of CD14 expression, and inhibited production of IL-β, IL-12p70, IL-23, and IL-27. In contrast, the expression of CD26, tolerogenic DC markers (ILT4 and IDO1), and production of immunoregulatory cytokines (IL-10 and TGF-β) were increased. Generally, the sita 0d protocol was more efficient. Sitagliptin-treated MoDCs were poorer allostimulators of T-cells in MoDC/T-cell co-culture and inhibited Th1 and Th17 but augmented Th2 and Treg responses. Tolerogenic properties of sitagliptin-treated MoDCs were additionally confirmed by an increased frequency of CD4+CD25+CD127- FoxP3+ Tregs and Tr1 cells (CD4+IL-10+FoxP3-) in MoDC/T-cell co-culture. The differentiation of IL-10+ and TGF-β+ Tregs depended on the sitagliptin protocol used. A Western blot analysis showed that sitagliptin inhibited p65 expression of NF-kB and p38MAPK during the maturation of MoDCs. In conclusion, sitagliptin induces differentiation of tolerogenic DCs, and the effect is important when considering sitagliptin for treating autoimmune diseases and allotransplant rejection.

Defective Induction of IL-27-Mediated Immunoregulation by Myeloid DCs in Multiple Sclerosis

The purpose of this study was to examine whether myeloid dendritic cells (mDCs) from patients with multiple sclerosis (MS) and healthy controls (HCs) become similarly tolerogenic when exposed to IL-27 as this may represent a potential mechanism of autoimmune dysregulation. Our study focused on natural mDCs that were isolated from HCs and MS patient peripheral blood mononuclear cells (PBMCs). After a 24-h treatment with IL-27 ± lipopolysaccharide (LPS), the mDCs were either harvested to identify IL-27-regulated gene expression or co-cultured with naive T-cells to measure how the treated DC affected T-cell proliferation and cytokine secretion. mDCs isolated from HCs but not untreated MS patients became functionally tolerogenic after IL-27 treatment. Although IL-27 induced both HC and untreated MS mDCs to produce similar amounts of IL-10, the tolerogenic HC mDCs expressed PD-L2, IDO1, and SOCS1, while the non-tolerogenic untreated MS mDCs expressed IDO1 and IL-6R. Cytokine and RNA analyses identified two signature blocks: the first identified genes associated with mDC tolerizing responses to IL-27, while the second was associated with the presence of MS. In contrast to mDCs from untreated MS patients, mDCs from HCs and IFNb-treated MS patients became tolerogenic in response to IL-27. The genes differentially expressed in the different donor IL-27-treated mDCs may contain targets that regulate mDC tolerogenic responses.

[The influence of fluoxetine on neuroimmune interaction in multiple sclerosis]

OBJECTIVE

To study the effect of fluoxetine on Th17- and Th1-immune response, which plays an important role in the pathogenesis of multiple sclerosis (MS).

MATERIAL AND METHODS

Ten patients with relapsing-remitting MS and ten healthy subjects were examined. The functions of Th17- and Th1-immune responses were assessed by the production of cytokines interleukin-17 (IL-17) and interferon-gamma (IFN-γ) by CD4+ T cells stimulated with macrophages or microbeads coated with anti-CD3 and anti-CD28-antibodies. To assess the effect of fluoxetine on the macrophages-induced Th17- and Th1-immune response, macrophages were pre-incubated in the presence of fluoxetine and co-cultured with autologous CD4+ T-cells. In the case of stimulation of CD4+ T-cells with anti-CD3/CD28-microbeads, fluoxetine was added directly to the T-helper cells before adding of microbeads. In addition, we evaluated the effect of fluoxetine on the production of the factors of differentiation of Th17-cells cytokines IL-6 and IL-1β by macrophages. The levels of cytokines in the cell culture supernatants were measured by ELISA.

RESULTS

The production of IL-17 and IFN-γ by CD4+ T-cells stimulated with macrophages or anti-CD3/CD28-microbeads was comparable between the groups. Fluoxetine suppressed the production of IL-17 and IFN-γ by anti-CD/CD28-stimulated CD4+ T-cells in both groups. Fluoxetine also suppressed the production of IL-6 and IL-1β by macrophages as well as their ability to induce IL-17 and IFN-γ production by CD4+ T-cells in both groups.

CONCLUSIONS

Fluoxetine may have an anti-inflammatory effect in MS that could be mediated by suppression of Th17- and Th1-cells or macrophage-induced Th17- and Th1-immune response.

Targeted delivery of a STING agonist to brain tumors using bioengineered protein nanoparticles for enhanced immunotherapy

Immunotherapy is emerging as a powerful tool for combating many human diseases. However, the application of this life-saving treatment in serious brain diseases, including glioma, is greatly restricted. The major obstacle is the lack of effective technologies for transporting therapeutic agents across the blood-brain barrier (BBB) and achieving targeted delivery to specific cells once across the BBB. Ferritin, an iron storage protein, traverses the BBB via receptor-mediated transcytosis by binding to transferrin receptor 1 (TfR1) overexpressed on BBB endothelial cells. Here, we developed bioengineered ferritin nanoparticles as drug delivery carriers that enable the targeted delivery of a small-molecule immunomodulator to achieve enhanced immunotherapeutic efficacy in an orthotopic glioma-bearing mouse model. We fused different glioma-targeting moieties on self-assembled ferritin nanoparticles via genetic engineering, and RGE fusion protein nanoparticles (RGE-HFn NPs) were identified as the best candidate. Furthermore, RGE-HFn NPs encapsulating a stimulator of interferon genes (STING) agonist (SR717@RGE-HFn NPs) maintained stable self-assembled structure and targeting properties even after traversing the BBB. In the glioma-bearing mouse model, SR717@RGE-HFn NPs elicited a potent local innate immune response in the tumor microenvironment, resulting in significant tumor growth inhibition and prolonged survival. Overall, this biomimetic brain delivery platform offers new opportunities to overcome the BBB and provides a promising approach for brain drug delivery and immunotherapy in patients with glioma.

RGE-HFn NPs showed excellent glioma-targeting ability.

RGE-HFn NPs showed potent tumor tissue-penetration ability.

SR717@RGE-HFn NPs effectively activated the STING pathway and exerted immunoregulatory effects within the intracranial glioma TME.

SR717@RHE-HFn NPs significantly triggered a glioma-specific innate immune response and remarkably delayed the growth of orthotopic gliomas without exhibiting apparent systemic toxicity.

Systemic nano-delivery of low-dose STING agonist targeted to CD103+ dendritic cells for cancer immunotherapy

Current methods of STING activation based on intra-tumoral injections of cyclic dinucleotides (CDNs) are not suitable for addressing tumor heterogeneity or for inaccessible, metastatic and abscopal tumors. In this study, we developed systemically administered CD103+ dendritic cell (DCs) targeted liposomal formulations and evaluated the anti-tumor efficacy with low dose. Liposomal CDN formulations were prepared using Clec9a targeting peptide and evaluated therapeutic efficacy in vitro and in vivo in subcutaneous MC38 and B16F10 tumor models. Targeted delivery of CDNs is expected to enhance anti-tumor immune response as well as reduce off-target toxicities. With intravenous 0.1 mg/kg systemic CDN dose of the targeted liposomal formulation, our results showed robust immune response with significant antitumor efficacy both as a monotherapy and in combination with anti-PD-L1 antibody. These results show that a CD103+ DC targeted CDN formulation can lead to potent immune stimulation upon systemic administration even in relatively "cold" tumors such as B16F10.

CCR7 as a therapeutic target in Cancer

The CCR7 chemokine axis is comprised of chemokine ligand 21 (CCL21) and chemokine ligand 19 (CCL19) acting on chemokine receptor 7 (CCR7). This axis plays two important but apparently opposing roles in cancer. On the one hand, this axis is significantly engaged in the trafficking of a number of effecter cells involved in mounting an immune response to a growing tumour. This suggests therapeutic strategies which involve potentiation of this axis can be used to combat the spread of cancer. On the other hand, the CCR7 axis plays a significant role in controlling the migration of tumour cells towards the lymphatic system and metastasis and can thus contribute to the expansion of cancer. This implies that therapeutic strategies which involve decreasing signaling through the CCR7 axis would have a beneficial effect in preventing dissemination of cancer. This dichotomy has partly been the reason why this axis has not yet been exploited, as other chemokine axes have, as a therapeutic target in cancer. Recent report of a crystal structure for CCR7 provides opportunities to exploit this axis in developing new cancer therapies. However, it remains unclear which of these two strategies, potentiation or antagonism of the CCR7 axis, is more appropriate for cancer therapy. This review brings together the evidence supporting both roles of the CCR7 axis in cancer and examines the future potential of each of the two different therapeutic approaches involving the CCR7 axis in cancer.

The influence of glatiramer acetate on Th17-immune response in multiple sclerosis

Glatiramer acetate (GA) is approved for the treatment of multiple sclerosis (MS). However, the mechanism of action of GA in MS is still unclear. In particular, it is not known whether GA can modulate the pro-inflammatory Th17-type immune response in MS. We investigated the effects of original GA (Copaxone^®, Teva, Israel) and generic GA (Timexone^®, Biocad, Russia) on Th17- and Th1-type cytokine production in vitro in 25 patients with relapsing-remitting MS and 25 healthy subjects. Both original and generic GA at concentrations 50–200 μg/ml dose-dependently inhibited interleukin-17 and interferon-γ production by anti-CD3/anti-CD28-activated peripheral blood mononuclear cells from MS patients and healthy subjects. This effect of GA was reproduced using purified CD4⁺ T cells, suggesting that GA can directly modulate the functions of Th17 and Th1 cells. At high concentrations (100–200 μg/ml), GA also suppressed the production of Th17-differentiation cytokines (interleukin-1β and interleukin-6) by lipopolysaccharide (LPS)-activated dendritic cells (DCs). These GA/LPS-treated DCs induced lower interleukin-17 and interferon-γ production by autologous CD4⁺ T cells compared to LPS-treated DCs. These data suggest that GA can inhibit Th17-immune response and that this inhibitory effect is preferentially exercised by direct influence of GA on T cells. We also demonstrate a comparable ability of original and generic GA to modulate pro-inflammatory cytokine production.

Engineered PLGA microparticles for long-term, pulsatile release of STING agonist for cancer immunotherapy

Activation of the stimulator of interferon gene (STING) pathway within the tumor microenvironment has been shown to generate a strong antitumor response. Although local administration of STING agonists has promise for cancer immunotherapy, the dosing regimen needed to achieve efficacy requires frequent intratumoral injections over months. Frequent dosing for cancer treatment is associated with poor patient adherence, with as high as 48% of patients failing to comply. Multiple intratumoral injections also disrupt the tumor microenvironment and vascular networks and therefore increase the risk of metastasis. Here, we developed microfabricated polylactic-co-glycolic acid (PLGA) particles that remain at the site of injection and release encapsulated STING agonist as a programmable sequence of pulses at predetermined time points that mimic multiple injections over days to weeks. A single intratumoral injection of STING agonist-loaded microparticles triggered potent local and systemic antitumor immune responses, inhibited tumor growth, and prolonged survival as effectively as multiple soluble doses, but with reduced metastasis in several mouse tumor models. STING agonist-loaded microparticles improved the response to immune checkpoint blockade therapy and substantially decreased the tumor recurrence rate from 100 to 25% in mouse models of melanoma when administered during surgical resection. In addition, we demonstrated the therapeutic efficacy of STING microparticles on an orthotopic pancreatic cancer model in mice that does not allow multiple intratumoral injections. These findings could directly benefit current STING agonist therapy by decreasing the number of injections, reducing risk of metastasis, and expanding its applicability to hard-to-reach cancers.

Interleukin-6-knockdown of chimeric antigen receptor-modified T cells significantly reduces IL-6 release from monocytes

Background

T cells expressing a chimeric antigen receptor (CAR) engineered to target CD19 can treat leukemia effectively but also increase the risk of complications such as cytokine release syndrome (CRS) and CAR T cell related encephalopathy (CRES) driven by interleukin-6 (IL-6). Here, we investigated whether IL-6 knockdown in CART-19 cells can reduce IL-6 secretion from monocytes, which may reduce the risk of adverse events.

Methods

Supernatants from cocultures of regular CART-19 cells and B lymphoma cells were added to monocytes in vitro, and the IL-6 levels in monocyte supernatants were measured 24 h later. IL-6 expression was knocked down in regular CART-19 cells by adding a short hairpin RNA (shRNA) (termed ssCART-19) expression cassette specific for IL-6 to the conventional CAR vector. Transduction efficiency and cell proliferation were measured by flow cytometry, and cytotoxicity was measured by evaluating the release of lactate dehydrogenase into the medium. Gene expression was assessed by qRT-PCR and RNA sequencing. A xenograft leukemia mouse model was established by injecting NOD/SCID/γc-/- mice with luciferase-expressing B lymphoma cells, and then the animals were treated with regular CART-19 cells or ssCART-19. Tumor growth was assessed by bioluminescence imaging.

Results

Both recombinant IL-6 and CART-19 derived IL-6 significantly triggered IL-6 release by monocytes. IL-6 knockdown in ssCART-19 cells dramatically reduced IL-6 release from monocytes in vitro stduy. In vivo study further demonstrated that the mice bearing Raji cells treated with ssCART-19 cells showed significant lower IL-6 levels in serum than those treated with regular CART-19 cells, but comparable anti-tumor efficacy between the animal groups.

Conclusion

CAR T-derived IL-6 is one of the most important initiators to amplify release of IL-6 from monocytes that further drive sCRS development. IL-6 knockdown in ssCART-19 cells by shRNA technology provide a promising strategy to improve the safety of CAR T cell therapy.

The PAPHIO study protocol: a randomised controlled trial with a 2 x 2 crossover design of physical activity adherence, psychological health and immunological outcomes in breast cancer survivors

BACKGROUND

The PAPHIO study; a randomized controlled trial with 2X2 crossover design will implement a self-directed physical activity program in which participants will engage in self-monitoring and receive motivational interviewing to enhance physical activity adherence. The study aims to determine the effects of 24 weeks self-directed activity combined with motivational interviewing (MI) on (i) psychological health, (ii) quality of life (QoL) and (iii) immune function in female breast cancer survivors.

METHODS

The study will recruit 64 female breast cancer survivors within 3 years of diagnosis and at least 6 months post primary treatments at Western Health Sunshine Hospital, Melbourne, Australia. They will be randomly allocated to immediate intervention (IIG group) or delayed intervention groups (DIG group) in a 1:1 ratio. All participants will be given a wearable device (Fitbit Alta HR) and undertake self-directed physical activity for 24 weeks and will receive MI for 12 weeks (IIG; during week 0 to week 12 and DIG; during week 13 to week 24). Participants' daily step count and the changes of immune cell functionality will be assessed at the beginning (week 1: T1), week 12 (T2) and week 24 (T3) of the program. Physical activity adherence will be assessed at T2 and T3. Participants will also complete four questionnaires assessing exercise self-regulation (BREQ2), exercise barrier and task self-efficacy, mental health (DASS-21) and QoL (FACT-B) at three time points (T1 to T3). Linear-mixed models will be used to assess the relationship between physical activity volume by step counting and mental health (DASS-21), QoL (FACT-B), immune biomarkers, self-regulation (BREQ2) and self-efficacy at T1, T2 and T3;between 2 groups.

DISCUSSION

We expect this physical activity intervention to be acceptable and beneficial to the participants in terms of psychological and immunological well-being with the potential outcomes to be implemented more widely at relatively low cost to these or other patient populations.

TRIAL REGISTRATION

Australian New Zealand Clinical trials Registry- ACTRN12619001271190. Prospectively registered on 13 September 2019.

Astragalus polysaccharides (PG2) Enhances the M1 Polarization of Macrophages, Functional Maturation of Dendritic Cells, and T Cell-Mediated Anticancer Immune Responses in Patients with Lung Cancer

Background: Recently, we demonstrated that Astragalus polysaccharide (PG2), the active ingredient in dried roots of astragalus membranaceus, ameliorates cancer symptom clusters and improves quality of life (QoL) in patients with metastatic disease by modulating inflammatory cascade against the background roles of inflammatory cells, including macrophages, dendritic cells (DCs), and cytotoxic T lymphocytes (CTLs) in tumor initiation, metastasis, and progression. Nevertheless, the role of PG2 in the modulation of anticancer immunogenicity and therapeutic response remains relatively underexplored and unclear. Purpose: The present study investigates how and to what extent PG2 modulates cellular and biochemical components of the inflammatory cascade and enhances anticancer immunity, as well as the therapeutic implication of these bio-events in patients with lung cancer. Methods and Results: Herein, we demonstrated that PG2 significantly increased the M1/M2 macrophage polarization ratio in non-small cell carcinoma (NSCLC) H441 and H1299 cells. This PG2-induced preferential pharmacologic up-regulation of tumoral M1 population in vitro positively correlated with the downregulation of tumor-promoting IL-6 and IL-10 expression in NSCLC cell-conditioned medium, with concomitant marked inhibition of cell proliferation, clonogenicity, and tumorsphere formation. Our ex vivo results, using clinical sample from our NSCLC cohort, demonstrated that PG2 also promoted the functional maturation of DCs with consequent enhancement of T cell-mediated anticancer immune responses. Consistent with the in vitro and ex vivo results, our in vivo studies showed that treatment with PG2 elicited significant time-dependent depletion of the tumor-associated M2 population, synergistically enhanced the anti-M2-based anticancer effect of cisplatin, and inhibited xenograft tumor growth in the NSCLC mice models. Moreover, in the presence of PG2, cisplatin-associated dyscrasia and weight-loss was markedly suppressed. Conclusion: These results do indicate a therapeutically-relevant role for PG2 in modulating the M1/M2 macrophage pool, facilitating DC maturation and synergistically enhancing the anticancer effect of conventional chemotherapeutic agent, cisplatin, thus laying the foundation for further exploration of the curative relevance of PG2 as surrogate immunotherapy and/or clinical feasibility of its use for maintenance therapy in patients with lung cancer.

An Anticancer Drug Cocktail of Three Kinase Inhibitors Improved Response to a Dendritic Cell-Based Cancer Vaccine

Monocyte-derived dendritic cell (moDC)-based cancer therapies intended to elicit antitumor T-cell responses have limited efficacy in most clinical trials. However, potent and sustained antitumor activity in a limited number of patients highlights the therapeutic potential of moDCs. In vitro culture conditions used to generate moDCs can be inconsistent, and moDCs generated in vitro are less effective than natural DCs. On the basis of our study highlighting the ability for certain kinase inhibitors to enhance tumor antigenicity, we therefore screened kinase inhibitors for their ability to improve DC immunogenicity. We identified AKT inhibitor MK2206, DNA-PK inhibitor NU7441, and MEK inhibitor trametinib as the compounds most effective at modulating moDC immunogenicity. The combination of these drugs, referred to as MKNUTRA, enhanced moDC activity over treatment with individual drugs while exhibiting minimal toxicity. An evaluation of 335 activation and T-cell-suppressive surface proteins on moDCs revealed that MKNUTRA treatment more effectively matured cells and reduced the expression of tolerogenic proteins as compared with control moDCs. MKNUTRA treatment imparted to ICT107, a glioblastoma (GBM) DC-based vaccine that has completed phase II trials, an increased ability to stimulate patient-derived autologous CD8+ T cells against the brain tumor antigens IL13Rα2(345-354) and TRP2(180-188) In vivo, treating ICT107 with MKNUTRA, prior to injection into mice with an established GBM tumor, reduced tumor growth kinetics. This response was associated with an increased frequency of tumor-reactive lymphocytes within tumors and in peripheral tissues. These studies broaden the application of targeted anticancer drugs and highlight their ability to increase moDC immunogenicity.

Enhancing Antigen Cross-Presentation in Human Monocyte-Derived Dendritic Cells by Recruiting the Intracellular Fc Receptor TRIM21

Suboptimal immune responses to pathogens contribute to chronic infections. One way to improve immune responses is to boost Ag presentation. In this study, we investigate the potential of the tripartite motif-containing 21 (TRIM21) pathway. TRIM21 is a ubiquitously expressed cytosolic protein that recognizes the Fc region of Abs. When Abs that are bound to pathogens enter the cell as immune complexes, binding of TRIM21 to Fc initiates downstream inflammatory signaling and targets the immune complexes for proteasomal degradation. In APCs, peptides generated by proteasomes are loaded onto MHC class I molecules to stimulate CD8 T cell responses, which are crucial for effective immunity to pathogens. We hypothesized that increasing the affinity between immune complexes and TRIM21 might markedly improve CD8 T cell responses to Ags processed by the TRIM21 pathway. Using phage display technology, we engineered the human IgG1 Fc to increase its affinity for TRIM21 by 100-fold. Adenovirus immune complexes with the engineered Fc induced greater maturation of human dendritic cells (DC) than immune complexes with unmodified Fc and stimulated increased Ag-specific CD8 T cell proliferation and IFN-γ release in cocultures of DC-PBMC. Thus, by increasing the affinity between Fc and TRIM21, Ags from immune complexes undergo enhanced cross-presentation on DC, leading to greater CD8 T cell responses. Our study reveals an approach that could potentially be used in vaccines to increase cytotoxic T cell responses against Ags that are targeted or delivered by Fc-modified Abs.

Exposure to Low-Dose Radiation Enhanced the Antitumor Effect of a Dendritic Cell Vaccine

The unsatisfactory clinical efficacy of dendritic cell (DC)-based cancer vaccines prepared by conventional methods is partly due to their insufficient capacity for migration. Our previous study showed that exposure to low-dose radiation (LDR) at a dose of 0.2 Gy promoted DC migration in vitro. The present study further investigates whether exposure to LDR at a dose of 0.2 Gy during the DC vaccine preparation could increase the antitumor effect of DC vaccines derived from mouse bone marrow. Our results showed that the migratory capacities of DCs were significantly increased after exposure to LDR. Furthermore, exposure to LDR resulted in an increased ability of DCs to induce T-cell proliferation, and the cytotoxic effect of cytotoxic T lymphocytes (CTLs) primed by the DCs exposed to LDR was significantly enhanced. An in vivo study using a mouse transplanted tumor model showed that subcutaneous injections of a DC vaccine exposed to LDR led to an increased mouse survival rate, infiltration of CTLs into tumor tissue, and apoptosis of tumor cells, which were accompanied by significant upregulation of serum interferon γ and interleukin 12. These results indicate that exposing DCs to LDR during the DC vaccine preparation is an effective approach to enhance its antitumor effect.

Immunogenic potential of three transmissible venereal tumor cell lysates to prime canine-dendritic cells for cancer immunotherapy

Whole tumor cell lysates consist of a mixture of tumor antigens and danger associated molecular patterns (DAMPs) that can be used for dendritic cell maturation and consequently for the activation of a polyclonal T cell-specific tumor response. We evaluated the in vitro efficacy of three different preparations of canine transmissible venereal tumor (TVT) cell lysates: hypochlorous acid-whole tumor cell lysates (HOCl-L), heat shock-whole tumor cell lysates (HS-L), and freeze-thaw cycles-whole tumor cell lysates (FT-L) for the maturation of canine-derived dendritic cells. Our results showed calreticulin, HSP70, and HSP90 release in the three tumor lysates preparations (HOCl-L, HS-L, and FT-L); however, HMGB1 was detected only in HOCl-L and FT-L. Additionally, the uptake by HOCl-L pulsed dendritic cell (DC) increased compared to HS-L and FT-L pulsed DC; and dendritic cell maturation was confirmed by the appropriate cell surface markers (CD11c, CD80, CD83, and MHCII). Furthermore, dendritic cells pulsed with HOCl-L, HS-L or FT-L were cultured with canine lymphocytes. There was an increase of Th1-type cytokines (IL-12, TNF-α, and IFN-γ), in all the tumor cell lysates co-cultures, this correlates with T lymphocyte activation and cytotoxic response. Our data confirm that TVT cell lysates can induce functional canine-DC and that HOCl-L is the most effective one. This preparation of TVT cell lysates with HOCl is an attractive approach that allows the recognition of neoantigens as potential tumor targets and DC priming and therefore could be used for cancer immunotherapy against TVT.

Dendritic Cell-Based Immunotherapy for Solid Tumors

As a treatment for solid tumors, dendritic cell (DC)-based immunotherapy has not been as effective as expected. Here, we review the reasons underlying the limitations of DC-based immunotherapy for solid tumors and ask what can be done to improve immune cell-based cancer therapies. Several reports show that, rather than a lack of immune induction, the limited efficacy of DC-based immunotherapy in cases of renal cell carcinoma (RCC) likely results from inhibition of immune responses by tumor-secreted TGF-β and an increase in the number of regulatory T (Treg) cells in and around the solid tumor. Indeed, unlike DC therapy for solid tumors, cytotoxic T lymphocyte (CTL) responses induced by DC therapy inhibit tumor recurrence after surgery; CTL responses also limit tumor metastasis induced by additional tumor-challenge in RCC tumor-bearing mice. Here, we discuss the mechanisms underlying the poor efficacy of DC-based therapy for solid tumors and stress the need for new and improved DC immunotherapies and/or combination therapies with killer cells to treat resistant solid tumors.

Immune Consequences of in vitro Infection of Human Peripheral Blood Leukocytes with Vesicular Stomatitis Virus

BACKGROUND

Oncolytic vesicular stomatitis virus (VSV) can be delivered intravenously to target primary and metastatic lesions, but the interaction between human peripheral blood leukocytes (PBLs) and VSV remains poorly understood. Our study aimed to assess the overall immunological consequences of ex vivo infection of PBLs with VSV.

METHODS

Phenotypic analysis of lymphocyte subsets and apoptosis were evaluated with flow cytometry. Caspase 3/7 activity was detected by luminescence assay. Virus release was evaluated in a murine cell line (L929). Gene expression and cytokine/chemokine secretion were assessed by real-time PCR and multiplex assay, respectively.

RESULTS

Ex vivo infection of PBLs with VSV elicited upregulated expression of RIG-I, MDA-5, tetherin, IFITM3, and MxA. VSV infection triggered rapid differentiation of blood monocytes into immature dendritic cells as well as their apoptosis, which depended on caspase 3/7 activation. Monocyte differentiation required infectious VSV, but loss of CD14+ cells was also associated with the presence of a cytokine/chemokine milieu produced in response to VSV infection.

CONCLUSIONS

Systemic delivery is a major goal in the field of oncolytic viruses. Our results shed further light on immune mechanisms in response to VSV infection and the underlying VSV-PBL interactions bringing hope for improved cancer immunotherapies, particularly those based on intravenous delivery of oncolytic VSV.

p21 Restricts HIV-1 in Monocyte-Derived Dendritic Cells through the Reduction of Deoxynucleoside Triphosphate Biosynthesis and Regulation of SAMHD1 Antiviral Activity

HIV-1 infection of noncycling cells, such as dendritic cells (DCs), is impaired due to limited availability of deoxynucleoside triphosphates (dNTPs), which are needed for HIV-1 reverse transcription. The levels of dNTPs are tightly regulated during the cell cycle and depend on the balance between dNTP biosynthesis and degradation. SAMHD1 potently blocks HIV-1 replication in DCs, although the underlying mechanism is still unclear. SAMHD1 has been reported to be able to degrade dNTPs and viral nucleic acids, which may both hamper HIV-1 reverse transcription. The relative contribution of these activities may differ in cycling and noncycling cells. Here, we show that inhibition of HIV-1 replication in monocyte-derived DCs (MDDCs) is associated with an increased expression of p21cip1/waf, a cell cycle regulator that is involved in the differentiation and maturation of DCs. Induction of p21 in MDDCs decreases the pool of dNTPs and increases the antiviral active isoform of SAMHD1. Although both processes are complementary in inhibiting HIV-1 replication, the antiviral activity of SAMHD1 in our primary cell model appears to be, at least partially, independent of its dNTPase activity. The reduction in the pool of dNTPs in MDDCs appears rather mostly due to a p21-mediated suppression of several enzymes involved in dNTP synthesis (i.e., RNR2, TYMS, and TK-1). These results are important to better understand the interplay between HIV-1 and DCs and may inform the design of new therapeutic approaches to decrease viral dissemination and improve immune responses against HIV-1.IMPORTANCE DCs play a key role in the induction of immune responses against HIV. However, HIV has evolved ways to exploit these cells, facilitating immune evasion and virus dissemination. We have found that the expression of p21, a cyclin-dependent kinase inhibitor involved in cell cycle regulation and monocyte differentiation and maturation, potentially can contribute to the inhibition of HIV-1 replication in monocyte-derived DCs through multiple mechanisms. p21 decreased the size of the intracellular dNTP pool. In parallel, p21 prevented SAMHD1 phosphorylation and promoted SAMHD1 dNTPase-independent antiviral activity. Thus, induction of p21 resulted in conditions that allowed the effective inhibition of HIV-1 replication through complementary mechanisms. Overall, p21 appears to be a key regulator of HIV infection in myeloid cells.

Enhanced stimulation of human tumor-specific T cells by dendritic cells matured in the presence of interferon-γ and multiple toll-like receptor agonists

Dendritic cell (DC) vaccines have been demonstrated to elicit immunological responses in numerous cancer immunotherapy trials. However, long-lasting clinical effects are infrequent. We therefore sought to establish a protocol to generate DC with greater immunostimulatory capacity. Immature DC were generated from healthy donor monocytes by culturing in the presence of IL-4 and GM-CSF and were further differentiated into mature DC by the addition of cocktails containing different cytokines and toll-like receptor (TLR) agonists. Overall, addition of IFNγ and the TLR7/8 agonist R848 during maturation was essential for the production of high levels of IL-12p70 which was further augmented by adding the TLR3 agonist poly I:C. In addition, the DC matured with IFNγ, R848, and poly I:C also induced upregulation of several other pro-inflammatory and Th1-skewing cytokines/chemokines, co-stimulatory receptors, and the chemokine receptor CCR7. For most cytokines and chemokines the production was even further potentiated by addition of the TLR4 agonist LPS. Concurrently, upregulation of the anti-inflammatory cytokine IL-10 was modest. Most importantly, DC matured with IFNγ, R848, and poly I:C had the ability to activate IFNγ production in allogeneic T cells and this was further enhanced by adding LPS to the cocktail. Furthermore, epitope-specific stimulation of TCR-transduced T cells by peptide- or whole tumor lysate-loaded DC was efficiently stimulated only by DC matured in the full maturation cocktail containing IFNγ and the three TLR ligands R848, poly I:C, and LPS. We suggest that this cocktail is used for future clinical trials of anti-cancer DC vaccines.

Monocyte lineage-derived IL-6 does not affect chimeric antigen receptor T-cell function

BACKGROUND AIMS

Chimeric antigen receptor (CAR) T-cell therapy targeting CD19 has demonstrated remarkable success in targeting B-cell malignancies but is often complicated by serious systemic toxicity in the form of cytokine release syndrome (CRS). CRS symptoms are primarily mediated by interleukin 6 (IL-6), and clinical management has focused on inhibition of IL-6 signaling. The cellular source and function of IL-6 in CRS remain unknown.

METHODS

Using co-culture assays and data from patients on our clinical CAR T-cell trials, we investigated the cellular source of IL-6, as well as other CRS-associated cytokines, during CAR T-cell activation. We also explored the effect that IL-6 has on T-cell function.

RESULTS

We demonstrated that IL-6 is secreted by monocyte-lineage cells in response to CAR T-cell activation in a contact-independent mechanism upon T-cell engagement of target leukemia. We observed that the presence of antigen-presenting cell-derived IL-6 has no impact on CAR T-cell transcriptional profiles or cytotoxicity. Finally, we confirm that CAR T cells do not secrete IL-6 in vivo during clinical CRS.

DISCUSSION

These findings suggest that IL-6 blockade will not affect CD19 CAR T-cell-driven anti-leukemic cytotoxicity, permitting enhanced control of CRS while maintaining CAR T-cell efficacy.

The Role of Dendritic Cell Maturation in the Induction of Insulin-Dependent Diabetes Mellitus

Dendritic cells (DCs) are the dominant class of antigen-presenting cells in humans and are largely responsible for the initiation and guidance of innate and adaptive immune responses involved in maintenance of immunological homeostasis. Immature dendritic cells (iDCs) phagocytize pathogens and toxic proteins and in endosomal vesicles degrade them into small fragments for presentation on major histocompatibility complex (MHC) II receptor molecules to naïve cognate T cells (Th0). In addition to their role in stimulation of immunity, DCs are involved in the induction and maintenance of immune tolerance toward self-antigens. During activation, the iDCs become mature. Maturation begins when the DCs cease taking up antigens and begin to migrate from their location in peripheral tissues to adjacent lymph nodes or the spleen where during their continued maturation the DCs present stored antigens on surface MHCII receptor molecules to naive Th0 cells. During antigen presentation, the DCs upregulate the biosynthesis of costimulatory receptor molecules CD86, CD80, CD83, and CD40 on their plasma membrane. These activated DC receptor molecules bind cognate CD28 receptors presented on the Th0 cell membrane, which triggers DC secretion of IL-12 or IL-10 cytokines resulting in T cell differentiation into pro- or anti-inflammatory T cell subsets. Although basic concepts involved in the process of iDC activation and guidance of Th0 cell differentiation have been previously documented, they are poorly defined. In this review, we detail what is known about the process of DC maturation and its role in the induction of insulin-dependent diabetes mellitus autoimmunity.

Immune transcriptome reveals the mincle C-type lectin receptor acts as a partial replacement for TLR4 in lipopolysaccharide-mediated inflammatory response in barramundi (Lates calcarifer)

Fish represent the most diverse and abundant extant vertebrate infraclass. They are also one of the earliest divergent phyla with adaptive immunity based on antigen recognition by MHC and immunoglobulin. The aquaculture industry, which currently provides more than half of the fish for human consumption globally, has successfully exploited the adaptive immune system of fish through mass vaccination programs. However, vaccination against highly diverse antigens, mostly carbohydrates, such as capsular polysaccharides and lipopolysaccharide (LPS) is challenging. Fish have a subdued innate response to LPS, but adaptive response is generally high and type-specific. To better understand the link between initial innate response and early onset of adaptive immunity to carbohydrate antigens in the perciform barramundi (Lates calcarifer), an immune transcriptome was prepared from pronephros and spleen following vaccination with LPS and peptidoglycan. From 163,661 transcripts derived by Illumina mRNA-Seq, most grouped in neuronal, endocrine or immune system categories, suggesting a close relationship between the three systems. Moreover, digestive enzyme transcripts in spleen appeared to be highly inducible in barramundi. Most of the known TLRs were transcribed in the barramundi spleen and HK transcriptome, with the notable exception of TLR4, which is primarily responsible for LPS recognition in mammals. Several C-type lectin receptors were also identified, including CD209, CD205, and CLEC4E (Mincle). As Mincle has been shown to bind LPS and is abundant on dendritic cells, its role in response to LPS in barramundi was further investigated. A high dose of LPS induced TNF-alpha expression via Mincle. However, IL-6 regulation, whilst still regulated in response to LPS, did not depend upon the Mincle pathway, suggesting other routes of activation. This study thus suggests that Mincle acts as a partial substitute for TLR4 in barramundi in the processing of LPS.

Monocyte-derived dendritic cells from patients with cervical intraepithelial lesions

Immunotherapy with dendritic cells (DCs) is a great promise for the treatment of neoplasms. However, the obtainment and protocol of differentiation of these cells may depend on extrinsic factors such as the tumor itself. The aim of the present study was to verify the influence of cervical neoplasia on different protocols of differentiation of monocyte-derived DCs resulting in an increased maturation phenotype. A total of 83 women were included in the study. The patients were grouped in low-grade squamous intraepithelial lesion (LSIL) (n=30), high-grade squamous intraepithelial lesion (HSIL) (n=22), cervical cancer (n=10) and healthy patients (n=21) groups. The mononuclear cells of patients were subjected to three differentiation protocols. In protocol I (pI), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-4 and tumor necrosis factor (TNF)-α were used for the differentiation of mature DCs (pIDCs). In protocol II (pII), monocytes were stimulated with GM-CSF, IL-4, TNF-α and activated lymphocytes in the absence of non-adherent cells (pIIDCs). In protocol III (pIII), monocytes were stimulated with GM-CSF, IL-4, TNF-α and activated lymphocytes in the presence of non-adherent cells (pIIIDCs). These cells were evaluated by flow cytometry for the expression of maturation markers such as cluster of differentiation (CD)11c, CD86 and human leukocyte antigen-antigen D related (HLA-DR). The main cytokines secreted (IL-4, IL-12 and transforming growth factor-β) were measured by ELISA. Our results indicate a significantly lower mature profile of pIIDCs and a significant increase in CD11c⁺ pIIIDCs able to produce IL-12 (P=0.0007). Furthermore, a significant reduction in cervical cancer HLA-DR⁺ pIDCs (P=0.0113) was also observed. HSIL patients exhibited a higher percentage of HLA-DR⁺ pIIDCs (P=0.0113), while LSIL patients had a lower percentage of CD11c⁺ pIIIDCs (P=0.0411). These findings suggest that the extent of cervical lesions affects the process of differentiation of DCs. Furthermore, activated lymphocytes may induce a better maturation of monocyte-derived DCs, and the presence of mononuclear cells appears to contribute to the DC differentiation process.

Comparative assessment of lipid based nano-carrier systems for dendritic cell based targeting of tumor re-initiating cells in gynecological cancers

We aimed to identify an optimum nano-carrier system to deliver tumor antigen to dendritic cells (DCs) for efficient targeting of tumor reinitiating cells (TRICs) in gynecological malignancies. Different lipid based nano-carrier systems i.e. liposomes, ethosomes and solid lipid nanoparticles (SLNPs) were examined for their ability to activate DCs in allogeneic settings. Out of these three, the most optimized formulation was subjected for cationic and mannosylated surface modification and pulsed with DCs for specific targeting of tumor cells. In both allogeneic and autologous trials, SLNPs showed a strong ability to activate DCs and orchestrate specific immune responses for targeting TRICs in gynecological malignancies. Our findings suggest that the mannosylated form of SLNPs is a suitable molecular vector for DC based therapeutics. DCs pulsed with mannosylated SLNPs may be utilized as adjuvant therapy for specific removal of TRICs to benefit patients from tumor recurrence.

Generation of potent porcine monocyte-derived dendritic cells (MoDCs) by modified culture protocol

In vitro derivation of dendritic cells (DCs) is an alternative approach to overcome the low frequency of primary DCs and the difficulty of isolation techniques for studying DC immunobiology. To date, the conventional culture protocol of porcine monocyte-derived DCs (MoDCs) has been widely used. However, this protocol is not practical due to the requirement of a substantial number of blood monocytes, and the process often interferes with DC maturation. To improve in vitro porcine MoDC generation, we modified the previous conventional DC generation protocol, based on the human and mouse primary DC culture system, and compared phenotypic and functional features of MoDCs derived from the modified protocol to the conventional protocol. The modified protocol consumed fewer monocytes but generated higher CD1⁺ cells with DC-like morphology and the ability of maturation. In addition, MoDCs from the modified protocol exhibited increased antigen uptake and IFN-γ production in response to LPS stimulation. Our findings indicate that the modified protocol is expedient and reliable for generating potent MoDCs that substitute for primary DCs. This will be a valuable platform for future research in antigen delivery, vaccines and immunotherapy in pigs, as well as relevant veterinary species.

Tolerogenic dendritic cells for reprogramming of lymphocyte responses in autoimmune diseases

Dendritic cells (DCs) control immune responses by driving potent inflammatory actions against external and internal threats while generating tolerance to self and harmless components. This duality and their potential to reprogram immune responses in an antigen-specific fashion have made them an interesting target for immunotherapeutic strategies to control autoimmune diseases. Several protocols have been described for in vitro generation of tolerogenic DCs (tolDCs) capable of modulating adaptive immune responses and restoring tolerance through different mechanisms that involve anergy, generation of regulatory lymphocyte populations, or deletion of potentially harmful inflammatory T cell subsets. Recently, the capacity of tolDCs to induce interleukin (IL-10)-secreting regulatory B cells has been demonstrated. In vitro assays and rodent models of autoimmune diseases provide insights to the molecular regulators and pathways enabling tolDCs to control immune responses. Here we review mechanisms through which tolDCs modulate adaptive immune responses, particularly focusing on their suitability for reprogramming autoreactive CD4⁺ effector T cells. Furthermore, we discuss recent findings establishing that tolDCs also modulate B cell populations and discuss clinical trials applying tolDCs to patients with autoimmune diseases.

Generation of Immature, Mature and Tolerogenic Dendritic Cells with Differing Metabolic Phenotypes

Immune response results from a complex interplay between the antigen non-specific innate immune system and the antigen specific adaptive immune system. The immune system is a constant balance in maintaining tolerance to self-molecules and reacting rapidly to pathogens. Dendritic cells (DCs) are powerful professional antigen presenting cells that link the innate immune system to the adaptive immune system and balance the adaptive response between self and non-self. Depending on the maturation signals, immature dendritic cells can be selectively stimulated to differentiate into immunogenic or tolerogenic DCs. Immunogenic dendritic cells provide proliferation signals to antigen-specific T cells for clonal expansion; while tolerogenic dendritic cells regulate tolerance by antigen-specific T-cell deletion or clonal expansion of regulatory T-cells. Due to this unique property, dendritic cells are highly sought after as therapeutic agents for cancer and autoimmune diseases. Dendritic cells can be loaded with specific antigens in vitro and injected into the human body to mount a specific immune response both immunogenic and tolerogenic. This work presents a means to generate in vitro from monocytes, immature monocyte derived dendritic cells (moDCs), tolerogenic and mature moDCs that differ in surface marker expression, function and metabolic phenotypes.

Gene Expression Profiling of Human Monocyte-derived Dendritic Cells - Searching for Molecular Regulators of Tolerogenicity

The ability of dendritic cells (DCs) to initiate and modulate antigen-specific immune responses has made them attractive targets for immunotherapy. Since DC research in humans is limited by the scarcity of DC populations in the blood circulation, most of our knowledge about DC biology and function has been obtained in vitro from monocyte-derived DCs (moDCs), which can be readily generated in sufficient numbers and are able to differentiate into distinct functional subsets depending on the nature of stimulus. In particular, moDCs with tolerogenic properties (tolDCs) possess great therapeutic potential for the treatment of autoimmune diseases. Several protocols have been developed to generate tolDCs in vitro, able to reinstruct auto-reactive T cells and to promote regulatory cells. While ligands and soluble mediators, by which DCs shape immune responses, have been vastly studied, the intracellular pathways and transcriptional regulators that govern tolDC differentiation and function are poorly understood. Whole-genome microarrays and proteomics provide useful strategies to dissect the complex molecular processes that promote tolerogenicity. Only few attempts have been made to understand tolDC biology through a global view on "omics" profiles. So far, the identification of a common regulator of tolerogenicity has been hampered by the fact that each protocol, used for tolDC generation, targets distinct signaling pathways. Here, we review the progress in understanding the transcriptional regulation of moDC differentiation, with a special focus on tolDCs, and highlight candidate molecules that might be associated with DC tolerogenicity.

Skewing dendritic cell differentiation towards a tolerogenic state for recovery of tolerance in rheumatoid arthritis

To date, the available options to treat autoimmune diseases such as rheumatoid arthritis (RA) include traditional corticoids and biological drugs, which are not exempt of adverse effects. The development of cellular therapies based on dendritic cells with tolerogenic functions (TolDCs) has opened a new possibility to efficiently eradicate symptoms and control the immune response in the field of autoimmunity. TolDCs are an attractive tool for antigen-specific immunotherapy to restore self-tolerance in RA and other autoimmune disorders. A promising strategy is to inject autologous self-antigen-loaded TolDCs, which are able to delete or reprogram autoreactive T cells. Different protocols for the generation of stable human TolDCs have been established and the therapeutic effect of TolDCs has been investigated in multiple rodent models of arthritis. Pilot studies in humans confirmed that TolDC application is safe, encouraging clinical trials using self-antigen-loaded TolDCs in RA patients. Although an abundance of molecular regulators of DC functions has been discovered in the last decade, no master regulator of tolerogenicity has been identified yet. Further research is required to define biomarkers or key regulators of tolerogenicity that might facilitate the induction and monitoring of TolDCs.

Timing and intensity of exposure to interferon-γ critically determines the function of monocyte-derived dendritic cells

A growing body of evidence suggests that inflammatory cytokines have a dualistic role in immunity. In this study, we sought to determine the direct effects of interferon-γ (IFN-γ) on the differentiation and maturation of human peripheral blood monocyte-derived dendritic cells (moDC). Here, we report that following differentiation of monocytes into moDC with granulocyte-macrophage colony-stimulating factor and interleukin-4, IFN-γ induces moDC maturation and up-regulates the co-stimulatory markers CD80/CD86/CD95 and MHC Class I, enabling moDC to effectively generate antigen-specific CD4(+) and CD8(+) T-cell responses for multiple viral and tumour antigens. Early exposure of monocytes to high concentrations of IFN-γ during differentiation promotes the formation of macrophages. However, under low concentrations of IFN-γ, monocytes continue to differentiate into dendritic cells possessing a unique gene-expression profile, resulting in impairments in subsequent maturation by IFN-γ or lipopolysaccharide and an inability to generate effective antigen-specific CD4(+) and CD8(+) T-cell responses. These findings demonstrate that IFN-γ imparts differential programmes on moDC that shape the antigen-specific T-cell responses they induce. Timing and intensity of exposure to IFN-γ can therefore determine the functional capacity of moDC.

Mesenchymal stem cell population derived from human pluripotent stem cells displays potent immunomodulatory and therapeutic properties

Mesenchymal stem cells (MSCs) are being tested in a wide range of human diseases; however, loss of potency and inconsistent quality severely limit their use. To overcome these issues, we have utilized a developmental precursor called the hemangioblast as an intermediate cell type in the derivation of a highly potent and replenishable population of MSCs from human embryonic stem cells (hESCs). This method circumvents the need for labor-intensive hand-picking, scraping, and sorting that other hESC-MSC derivation methods require. Moreover, unlike previous reports on hESC-MSCs, we have systematically evaluated their immunomodulatory properties and in vivo potency. As expected, they dynamically secrete a range of bioactive factors, display enzymatic activity, and suppress T-cell proliferation that is induced by either allogeneic cells or mitogenic stimuli. However, they also display unique immunophenotypic properties, as well as a smaller size and >30,000-fold proliferative capacity than bone marrow-derived MSCs. In addition, this is the first report which demonstrates that hESC-MSCs can inhibit CD83 up-regulation and IL-12p70 secretion from dendritic cells and enhance regulatory T-cell populations induced by interleukin 2 (IL-2). This is also the first report which shows that hESC-MSCs have therapeutic efficacy in two different autoimmune disorder models, including a marked increase in survival of lupus-prone mice and a reduction of symptoms in an autoimmune model of uveitis. Our data suggest that this novel and therapeutically active population of MSCs could overcome many of the obstacles that plague the use of MSCs in regenerative medicine and serve as a scalable alternative to current MSC sources.

Moraxella catarrhalis adhesin UspA1-derived recombinant fragment rD-7 induces monocyte differentiation to CD14+CD206+ phenotype

Circulating monocytes in the bloodstream typically migrate to other tissues and differentiate into tissue resident macrophages, the process being determined by the constituents of the microenvironments encountered. These may include microbes and their products. In this study, we investigated whether Moraxella catarrhalis Ubiquitous Surface Protein A1 (UspA1), known to bind to a widely expressed human cell surface receptor CEACAM1, influences monocyte differentiation as receptor engagement has been shown to have profound effects on monocytes. We used the recombinant molecules corresponding to the regions of UspA1 which either bind (rD-7; UspA1_527–665) or do not bind (r6–8; UspA1_659–863) to CEACAM1 and investigated their effects on CD206, CD80 and CD86 expression on freshly isolated human CD14+ monocytes from peripheral blood mononuclear cells (PBMC). Exposure to rD-7, but not r6–8, biased monocyte differentiation towards a CD14+CD206+ phenotype, with reduced CD80 expression. Monocytes treated with rD-7 also secreted high levels of IL-1ra and chemokine IL-8 but not IL-10 or IL-12p70. The effects of rD-7 were independent of any residual endotoxin. Unexpectedly, these effects of rD-7 were also independent of its ability to bind to CEACAM1, as monocyte pre-treatment with the anti-CEACAM antibody A0115 known to inhibit rD-7 binding to the receptor, did not affect rD-7-driven differentiation. Further, another control protein rD-7/D (a mutant form of rD-7, known not to bind to CEACAMs), also behaved as the parent molecule. Our data suggest that specific regions of M. catarrhalis adhesin UspA1 may modulate inflammation during infection through a yet unknown receptor on monocytes.

Molecular characterization of antigen-peptide pulsed dendritic cells: immature dendritic cells develop a distinct molecular profile when pulsed with antigen peptide

As dendritic cells (DCs) are the most potent professional antigen-presenting cells, they are being tested as cancer vaccines for immunotherapy of established cancers. Although numerous studies have characterized DCs by their phenotype and function, few have identified potential molecular markers of antigen presentation prior to vaccination of host. In this study we generated pre-immature DC (piDC), immature DC (iDC), and mature DC (mDC) from human peripheral blood monocytes (PBMC) obtained from HLA-A2 healthy donors, and pulsed them with human papillomavirus E7 peptide (p11-20), a class I HLA-A2 binding antigen. We then characterized DCs for cell surface phenotype and gene expression profile by microarray technology. We identified a set of 59 genes that distinguished three differentiation stages of DCs (piDC, iDC and mDC). When piDC, iDC and mDC were pulsed with E7 peptide for 2 hrs, the surface phenotype did not change, however, iDCs rather than mDCs showed transcriptional response by up-regulation of a set of genes. A total of 52 genes were modulated in iDC upon antigen pulsing. Elongation of pulse time for iDCs to 10 and 24 hrs did not significantly bring further changes in gene expression. The E7 peptide up-modulated immune response (KPNA7, IGSF6, NCR3, TREM2, TUBAL3, IL8, NFKBIA), pro-apoptosis (BTG1, SEMA6A, IGFBP3 and SRGN), anti-apoptosis (NFKBIA), DNA repair (MRPS11, RAD21, TXNRD1), and cell adhesion and cell migration genes (EPHA1, PGF, IL8 and CYR61) in iDCs. We confirmed our results by Q-PCR analysis. The E7 peptide but not control peptide (PADRE) induced up-regulation of NFKB1A gene only in HLA-A2 positive iDCs and not in HLA-A2 negative iDCs. These results suggest that E7 up-regulation of genes is specific and HLA restricted and that these genes may represent markers of antigen presentation and help rapidly assess the quality of dendritic cells prior to administration to the host.

Tumor-altered dendritic cell function: implications for anti-tumor immunity

Dendritic cells (DC) are key regulators of both innate and adaptive immunity, and the array of immunoregulatory functions exhibited by these cells is dictated by their differentiation, maturation, and activation status. Although a major role for these cells in the induction of immunity to pathogens has long been appreciated, data accumulated over the last several years has demonstrated that DC are also critical regulators of anti-tumor immune responses. However, despite the potential for stimulation of robust anti-tumor immunity by DC, tumor-altered DC function has been observed in many cancer patients and tumor-bearing animals and is often associated with tumor immune escape. Such dysfunction has significant implications for both the induction of natural anti-tumor immune responses as well as the efficacy of immunotherapeutic strategies that target endogenous DC in situ or that employ exogenous DC as part of anti-cancer immunization maneuvers. In this review, the major types of tumor-altered DC function will be described, with emphasis on recent insights into the mechanistic bases for the inhibition of DC differentiation from hematopoietic precursors, the altered programing of DC precursors to differentiate into myeloid-derived suppressor cells or tumor-associated macrophages, the suppression of DC maturation and activation, and the induction of immunoregulatory DC by tumors, tumor-derived factors, and tumor-associated cells within the milieu of the tumor microenvironment. The impact of these tumor-altered cells on the quality of the overall anti-tumor immune response will also be discussed. Finally, this review will also highlight questions concerning tumor-altered DC function that remain unanswered, and it will address factors that have limited advances in the study of this phenomenon in order to focus future research efforts in the field on identifying strategies for interfering with tumor-associated DC dysfunction and improving DC-mediated anti-tumor immunity.

Toll-like receptor 4 engagement drives differentiation of human and murine dendritic cells from a pro- into an anti-inflammatory mode

The dendritic cell (DC) coordinates innate and adaptive immunity to fight infections and cancer. Our observations reveal that DCs exposed to the microbial danger signal lipopolysaccharide (LPS) in the presence of interferon-γ (IFN-γ) acquire a continuously changing activation/maturation phenotype. The DCs’ initial mode of action is pro-inflammatory via up-regulation among others of the signaling molecule interleukin (IL) 12, which polarizes IFN-γ secreting type 1 helper T-cells (Th1). Within 24 hours the same DC switches from the pro- into an anti-inflammatory phenotype. This is mediated by autocrine IL-10 release and secretion of soluble IL-2 receptor alpha (sIL-2RA) molecules. T-cells, when contacted with DCs during their anti-inflammatory phase loose their proliferative capacity and develop regulatory T-cell (Treg) -like anti-inflammatory functions indicated by IL-10 secretion and elevated FoxP3 levels. Studying the kinetics of IL-12 and IL-10 expression from LPS/IFN-γ activated myeloid DCs on a single cell level confirmed these observations. When T-cells are separated from DCs within 24 hours, they are spared from the anti-inflammatory DC activity. We conclude that, in addition to differentiation of DCs into distinct subsets, the observed sequential functional phases of DC differentiation permit the fine-tuning of an immune response. A better understanding of time-kinetic DC features is required for optimally exploiting the therapeutic capacity of DCs in cancer immune therapy.

Immunoregulatory properties of rapamycin-conditioned monocyte-derived dendritic cells and their role in transplantation

In efforts to minimize the chronic administration of immunosuppression (IS) drugs in transplantation and autoimmune disease, various cell-based tolerogenic therapies, including the use of regulatory or tolerogenic dendritic cells (tolDC) have been developed. These DC-based therapies aim to harness the inherent immunoregulatory potential of these professional antigen-presenting cells. In this short review, we describe both the demonstrated tolerogenic properties, and current limitations of rapamycin-conditioned DC (RAPA-DC). RAPA-DC are generated through inhibition of the integrative kinase mammalian target of rapamycin (mTOR) by the immunosuppressive macrolide rapamycin during propagation of monocyte-derived DC. Consistent with the characteristics of tolDC, murine RAPA-DC display resistance to phenotypic maturation induced by pro-inflammatory stimuli; exhibit the ability to migrate to secondary lymphoid tissue (important for 'cross-presentation' of antigen to T cells), and enrich for naturally-occurring CD4+ regulatory T cells. In rodent models, delivery of recipient-derived RAPA-DC pulsed with donor antigen prior to organ transplantation can prolong allogeneic heart-graft survival indefinitely, especially when combined with a short course of IS. These encouraging data support ongoing efforts to develop RAPA-DC for clinical testing. When compared to murine RAPA-DC however, human RAPA-DC have proven only partially resistant to maturation triggered by pro-inflammatory cytokines, and display heterogeneity in their impact on effector T-cell expansion and function. In total, the evidence suggests the need for more in-depth studies to better understand the mechanisms by which mTOR controls human DC function. These studies may facilitate the development of RAPA-DC therapy alone or together with agents that preserve/enhance their tolerogenic properties as clinical immunoregulatory vectors.

Cell separation by countercurrent centrifugal elutriation: recent developments

Countercurrent centrifugal elutriation (CCE) is a cell separation technique that separates particles predominantly according to their size, and to some degree according to their specific density, without a need for antibodies or ligands tagging cell surfaces. The principles of this technique have been known for half a century. Still, numerous recent publications confirmed that CCE is a valuable supplement to current cell separation technology. It is mainly applied when homogeneous populations of cells, which mirror an in vivo situation, are required for answering scientific questions or for clinical transplantation, while antibodies or ligands suitable for cell isolation are not available. Currently, new technical developments are expanding its application toward fractionation of healthy and malignant tissue cells and the preparation of dendritic cells for immunotherapy.

15 kDa granulysin causes differentiation of monocytes to dendritic cells but lacks cytotoxic activity

Granulysin is expressed as two isoforms by human cytotoxic cells: a single mRNA gives rise to 15 kDa granulysin, a portion of which is cleaved to a 9 kDa protein. Studies with recombinant 9 kDa granulysin have demonstrated its cytolytic and proinflammatory properties, but much less is known about the biologic function of the 15 kDa isoform. In this study, we show that the subcellular localization and functions of 9 and 15 kDa granulysin are largely distinct. Nine kilodalton granulysin is confined to cytolytic granules that are directionally released following target cell recognition. In contrast, 15 kDa granulysin is located in distinct granules that lack perforin and granzyme B and that are released by activated cytolytic cells. Although recombinant 9 kDa granulysin is cytolytic against a variety of tumors and microbes, recombinant 15 kDa granulysin is not. The 15 kDa isoform is a potent inducer of monocytic differentiation to dendritic cells, but the 9 kDa isoform is not. In vivo, mice expressing granulysin show markedly improved antitumor responses, with increased numbers of activated dendritic cells and cytokine-producing T cells. Thus, the distinct functions of granulysin isoforms have major implications for diagnosis and potential new therapies for human disease.

Dendritic cells the tumor microenvironment and the challenges for an effective antitumor vaccination

Many clinical trials have been carried out or are in progress to assess the therapeutic potential of dendritic-cell- (DC-) based vaccines on cancer patients, and recently the first DC-based vaccine for human cancer was approved by the FDA. Herewith, we describe the general characteristics of DCs and different strategies to generate effective antitumor DC vaccines. In recent years, the relevance of the tumor microenvironment in the progression of cancer has been highlighted. It has been shown that the tumor microenvironment is capable of inactivating various components of the immune system responsible for tumor clearance. In particular, the effect of the tumor microenvironment on antigen-presenting cells, such as DCs, does not only render these immune cells unable to induce specific immune responses, but also turns them into promoters of tumor growth. We also describe strategies likely to increase the efficacy of DC vaccines by reprogramming the immunosuppressive nature of the tumor microenvironment.

Cancer vaccines. Any future?

The idea that vaccination can be used to fight cancer is not new. Approximately 100 years ago, researchers attempted to stimulate a tumor-specific, therapeutic immune response to tumors by injecting patients with cells and extracts from their own tumors, or tumors of the same type from different individuals. During the last decade, great efforts have been made to develop immunotherapeutic approaches for the treatment of malignant diseases as alternatives to traditional chemo- and radiotherapy. A quintessential goal of immunotherapy in cancer is treatment with vaccines that elicit potent anti-tumor immune responses without side effects. In this article, we have attempted to review some of the most problematic issues facing the development of cancer vaccines. With the prospect of immunosuppression, an ill-designed cancer vaccine can be more harmful than a no-benefit therapy. We have noted that "immunoediting" and "immunodominance" are the premier setbacks in peptide-based vaccines and therefore it appears necessary not only to manipulate the activity of a vast number of principal components but also to finely tune their concentrations in time and space. In the face of all these quandaries, it is at least doubtful that any reliable anti-cancer vaccine strategy will emerge in the near future.

Species-specific microRNA roles elucidated following astrocyte activation

MicroRNAs (miRNAs) are short non-coding RNAs that play a central role in regulation of gene expression by binding to target genes. Many miRNAs were associated with the function of the central nervous system (CNS) in health and disease. Astrocytes are the CNS most abundant glia cells, providing support by maintaining homeostasis and by regulating neuronal signaling, survival and synaptic plasticity. Astrocytes play a key role in repair of brain insults, as part of local immune reactivity triggered by inflammatory or pathological conditions. Thus, astrocyte activation, or astrogliosis, is an important outcome of the innate immune response, which can be elicited by endotoxins such as lipopolysaccharide (LPS) and cytokines such as interferon-gamma (IFN-γ). The involvement of miRNAs in inflammation and stress led us to hypothesize that astrogliosis is mediated by miRNA function. In this study, we compared the miRNA regulatory layer expressed in primary cultured astrocyte derived from rodents (mice) and primates (marmosets) brains upon exposure to LPS and IFN-γ. We identified subsets of differentially expressed miRNAs some of which are shared with other immunological related systems while others, surprisingly, are mouse and rat specific. Of interest, these specific miRNAs regulate genes involved in the tumor necrosis factor-alpha (TNF-α) signaling pathway, indicating a miRNA-based species-specific regulation. Our data suggests that miRNA function is more significant in the mechanisms governing astrocyte activation in rodents compared to primates.

Preparation and identification of a novel immunomodulator composed of muramyl dipeptide and anti-CD10 monoclonal antibody for treatment of minimal residual disease in acute leukemia children

Targeted therapy is a potentially useful approach for antileukemic therapy, in particular eliminating minimal residual disease (MRD) to prevent tumor relapse. In this study, the immunomodulator (MDP-Ab) was constructed by coupling anti-CD10 monoclonal antibody (MAb) and muramyl dipeptide (MDP) using heterobifunctional reagent SPDP and the activity of MDP-Ab through dendritic cells (DCs)-based immunotherapy was identified in targeted therapy for leukemia. Results showed that the molecular ratio of purified MDP-Ab immunomodulator was about 2:1 according to electrospray ionization mass spectrometry (ESI-MS). The immunoreactivity and specificity of the new immunomodulator on CD10 antigen was identical to that of unconjugated native anti-CD10 MAb. The immunomodulatory effect of MDP-Ab immunoconjugate on peripheral blood dendritic cells (PBDCs) from children with acute lymphoblastic leukemia (ALL) exhibited upregulated expression of HLA-DR, co-stimulatory marker (CD80 and CD86) and maturity marker (CD83), increased cytokine secretion (interleukin-12, IL-12) and enhanced autostimulatory activity. These results in vitro suggested that MDP-Ab immunoconjugate may be a suitable candidate for targeting trials and support the further development of vaccination with the new immunomodulator-triggered DCs as a post-remission treatment to prevent relapse in ALL children.

Three-day dendritic cells for vaccine development: antigen uptake, processing and presentation

BACKGROUND

Antigen-loaded dendritic cells (DC) are capable of priming naïve T cells and therefore represent an attractive adjuvant for vaccine development in anti-tumor immunotherapy. Numerous protocols have been described to date using different maturation cocktails and time periods for the induction of mature DC (mDC) in vitro. For clinical application, the use of mDC that can be generated in only three days saves on the costs of cytokines needed for large scale vaccine cell production and provides a method to produce cells within a standard work-week schedule in a GMP facility.

METHODS

In this study, we addressed the properties of antigen uptake, processing and presentation by monocyte-derived DC prepared in three days (3d mDC) compared with conventional DC prepared in seven days (7d mDC), which represent the most common form of DC used for vaccines to date.

RESULTS

Although they showed a reduced capacity for spontaneous antigen uptake, 3d mDC displayed higher capacity for stimulation of T cells after loading with an extended synthetic peptide that requires processing for MHC binding, indicating they were more efficient at antigen processing than 7d DC. We found, however, that 3d DC were less efficient at expressing protein after introduction of in vitro transcribed (ivt)RNA by electroporation, based on published procedures. This deficit was overcome by altering electroporation parameters, which led to improved protein expression and capacity for T cell stimulation using low amounts of ivtRNA.

CONCLUSIONS

This new procedure allows 3d mDC to replace 7d mDC for use in DC-based vaccines that utilize long peptides, proteins or ivtRNA as sources of specific antigen.