Targeting CXCR4 impaired T regulatory function through PTEN in renal cancer patients

BACKGROUND

Tregs trafficking is controlled by CXCR4. In Renal Cell Carcinoma (RCC), the effect of the new CXCR4 antagonist, R54, was explored in peripheral blood (PB)-Tregs isolated from primary RCC patients.

METHODS

PB-Tregs were isolated from 77 RCC patients and 38 healthy donors (HDs). CFSE-T effector-Tregs suppression assay, IL-35, IFN-γ, IL-10, TGF-β1 secretion, and Nrp-1+Tregs frequency were evaluated. Tregs were characterised for CTLA-4, PD-1, CD40L, PTEN, CD25, TGF-β1, FOXP3, DNMT1 transcriptional profile. PTEN-pAKT signalling was evaluated in the presence of R54 and/or triciribine (TCB), an AKT inhibitor. Methylation of TSDR (Treg-Specific-Demethylated-Region) was conducted.

RESULTS

R54 impaired PB-RCC-Tregs function, reduced Nrp-1+Tregs frequency, the release of IL-35, IL-10, and TGF-β1, while increased IFN-γ Teff-secretion. The CXCR4 ligand, CXCL12, recruited CD25+PTEN+Tregs in RCC while R54 significantly reduced it. IL-2/PMA activates Tregs reducing pAKT+Tregs while R54 increases it. The AKT inhibitor, TCB, prevented the increase in pAKT+Tregs R54-mediated. Moreover, R54 significantly reduced FOXP3-TSDR demethylation with DNMT1 and FOXP3 downregulation.

CONCLUSION

R54 impairs Tregs function in primary RCC patients targeting PTEN/PI3K/AKT pathway, reducing TSDR demethylation and FOXP3 and DNMT1 expression. Thus, CXCR4 targeting is a strategy to inhibit Tregs activity in the RCC tumour microenvironment.

CD8+CD103+PD1+TIM3+ T cells in glioblastoma microenvironment correlate with prognosis

Glioblastoma, isocitrate dehydrogenase-wildtype (GB), is the most common and aggressive primary brain malignancy with poor outcome. Immune checkpoint inhibitors (ICIs) have been tested in GB and, despite disappointing results, the identification of a small subgroup of responders underlies the need to improve our understanding of the tumour microenvironment (TME) immunity. This study aimed to determine whether the expression of selected immune checkpoints on tissue-resident memory T cells (Trm) may predict patient outcome. We conducted a single cohort observational study. Tumour samples were collected from 45 patients with histologically confirmed GB (WHO grade 4) and processed to obtain single-cell suspensions. Patients were assessed for the correlation of Trm phenotype with overall survival (OS) or progression-free survival (PFS) using multiparametric flow cytometry and uni/multivariate analyses. Levels of Trm expressing programmed cell death protein 1 (PD1) and T cell immunoglobulin and mucin domain-containing protein 3 (TIM3) were found to be linked to clinical outcome. Low frequency of Trm expressing PD1 or TIM3 or both markers defined subgroups as independent positive prognostic factors for patient survival. On multivariate analysis, low CD8+CD103+PD1+TIM3+ Trm and Karnofsky performance status (KPS) ≥70 were confirmed to be the most predictive independent factors associated with longer OS (hazard ratios-HR [95%CI]: 0.14 [0.04-0.52] p < 0.001, 0.39 [0.16-0.96] p = 0.04, respectively). The CD8+CD103+ Trm subgroups were also age-related predictors for survival in GB.

Reversing vemurafenib-resistance in primary melanoma cells by combined romidepsin and type I IFN treatment through blocking of tumorigenic signals and induction of immunogenic effects

BRAF^V600 mutations are the most common oncogenic alterations in melanoma cells, supporting proliferation, invasion, metastasis and immune evasion. In patients, these aberrantly activated cellular pathways are inhibited by BRAFi whose potent antitumor effect and therapeutic potential are dampened by the development of resistance. Here, by using primary melanoma cell lines, generated from lymph node lesions of metastatic patients, we show that the combination of two FDA-approved drugs, the histone deacetylate inhibitor (HDCAi) romidepsin and the immunomodulatory agent IFN-α2b, reduces melanoma proliferation, long-term survival and invasiveness and overcomes acquired resistance to the BRAFi vemurafenib (VEM). Targeted resequencing revealed that each VEM-resistant melanoma cell line and the parental counterpart are characterized by a distinctive and similar genetic fingerprint, shaping the differential and specific antitumor modulation of MAPK/AKT pathways by combined drug treatment. By using RNA-sequencing and functional in vitro assays, we further report that romidepsin-IFN-α2b treatment restores epigenetically silenced immune signals, modulates MITF and AXL expression and induces both apoptosis and necroptosis in sensitive and VEM-resistant primary melanoma cells. Moreover, the immunogenic potential of drug-treated VEM-resistant melanoma cells results significantly enhanced, given the increased phagocytosis rate of these cells by dendritic cells, which in turn exhibit also a selective down-modulation of the immune checkpoint TIM-3. Overall, our results provide evidence that combined epigenetic-immune drugs can overcome VEM resistance of primary melanoma cells by oncogenic and immune pathways reprogramming, and pave the way for rapidly exploiting this combination to improve BRAFi-resistant metastatic melanoma treatment, also via reinforcement of immune checkpoint inhibitor therapy.

Abstract 1353: Immunomodulatory effects of valproic acid in combination with cisplatin and cetuximab in head and neck squamous cell carcinoma

INTRODUCTION. Development of immune-check-point inhibitors (ICI) has greatly changed the treatment of recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) demonstrating durable antitumor response and overall survival (OS) improvement. However, more than 70% of patients do not respond to ICI and, recently, phase III Checkmate 651 trial did not demonstrate OS improvement of first-line ICI vs standard EXTREME regimen (cetuximab (CX) plus 5-fluorouracil/cisplatin (CDDP) in R/M HNSCC patients (ESMO2021-LBA36). We have previously showed in vitro and in vivo models of HNSCC the synergistic antitumor interaction of CDDP/CX combined with the antiepileptic valproic acid (VPA), a histone deacetylase inhibitor (HDACi) with anticancer and immunomodulatory properties (Iannelli F., 2020). Here we investigate the immunomodulatory effects of VPA/CDDP/CX combination, focusing on the induction of "immunogenic cell death" (ICD)-like features.

METHODS. ICD-related damage-associated molecular patterns (DAMPs) calreticulin (CARL), ATP, HMGB1 and Annexin-A1 (ANXA1) expression was evaluated by western blot, immunofluorescence and/or bioluminescent assays on HNSCC Cal27 and osteosarcoma U2OS cells. Maturation, migration, cytokines release, and phagocytic capacity of dendritic cells (IL4_DCs) was evaluated incubating IL4-DCs with conditioned medium from untreated/treated Cal27 cells and/or in co-culture IL4-DCs/Cal27 assays by ELISA, cytofluorimetric assays and confocal microscopy.

RESULTS. VPA/CDDP/CX combination induced in both U2OS and Cal27 cells, synergistic pre-apoptotic exposure of CARL along with HMGB1, ANXA1 and ATP release as compared with single drugs or doublet combination. Moreover, the triple combination increases IL4-DCs migration towards pretreated Cal27 cells as well as the rate of IL4-DCs phagocytosis of apoptotic bodies released by Cal27 dying cells. Triple combination also induces phenotypical maturation of DCs as shown by the increased surface expression of CD83 and CD86. Furthermore, conditioned medium from VPA/CDDP/CX treated Cal27 cells, induced increased release of immune-stimulating cytokines and chemokines IL2, IL1β, TNFα, MIP-1α and G-CSF by IL4-DCs as well as the impairment of immunosuppressive cytokines release IL-10 and VEGF, by VPA/CDDP/CX treated Cal27, co-cultured with IL4-DCs. In vivo experiments in immunocompetent syngeneic mouse model using HNSCC AT-84 cells transduced with human-EGFR are ongoing.

CONCLUSION. Overall, we demonstrated that VPA/CDDP/CX is able to enhance the immunogenicity of HNSCC model by inducing ICD. This mechanistic hypothesis will be tested by assessing ICD biomarkers on samples of patients enrolled in the V-CHANCE phase 2 clinical trial evaluating the CDDP/CX associated with VPA in R/M SCCHN patients and recently concluded (NCT02624128).

Citation Format: Federica Iannelli, Andrea Ilaria Zotti, Maria Serena Roca, Laura Grumetti, tania Moccia, carlo vitagliano, susan costantini, francesca capone, francesca collina, Lucia Gabriele, stefania parlato, Giulia Romagnoli, Oliver Kepp, Guido Kroemer, Elena Di Gennaro, Alfredo Budillon. Immunomodulatory effects of valproic acid in combination with cisplatin and cetuximab in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1353.

Anti-IFN-α/-ω neutralizing antibodies from COVID-19 patients correlate with downregulation of IFN response and laboratory biomarkers of disease severity

A significant number of COVID‐19 patients were shown to have neutralizing antibodies (NAB) against IFN; however, NAB specificity, fluctuation over time, associations with biochemical and hematological parameters, and IFN gene expression are not well characterized.

Binding antibodies (BAB) to IFN‐α/‐β were screened in COVID‐19 patients’ serum. All BAB positive sera, and a subset of respiratory samples, were tested for NAB against IFN‐α/‐β/‐ω, using an antiviral bioassay. Transcript levels of IFN‐α/‐β/‐ω and IFN‐stimulated genes (ISGs) were quantified.

Anti‐IFN‐I BAB were found in 61 out of 360 (17%) of patients. Among BAB positive sera, 21.3% had a high NAB titer against IFN‐α. A total of 69.2% of anti‐IFN‐α NAB sera displayed cross‐reactivity to IFN‐ω. Anti‐IFN‐I NAB persisted in all patients. NAB to IFN‐α were also detected in 3 out of 17 (17.6%) of respiratory samples. Anti‐IFN‐I NAB were higher in males (p = 0.0017), patients admitted to the ICU (p < 0.0001), and patients with a fatal outcome (p < 0.0001). NAB were associated with higher levels of CRP, LDH, d‐Dimer, and higher counts of hematological parameters. ISG‐mRNAs were reduced in patients with persistently NAB titer.

NAB are detected in a significant proportion of severe COVID‐19. NAB positive patients presented a defective IFN response and increased levels of laboratory biomarkers of disease severity.

Distribution of Interferon Lambda 4 Single Nucleotide Polymorphism rs11322783 Genotypes in Patients with COVID-19

Type III interferons (IFN-III), also known as IFN-Lambda, have a pivotal role during SARS-CoV-2 infection. IFN-Lambda response among individuals is heterogeneous and its association with COVID-19 symptoms severity needs to be further clarified. We analyzed the genotype frequencies of IFNL4 single nucleotide polymorphism (SNP) rs11322783 in patients with COVID-19 (n = 128), in comparison with a validated data set of European healthy controls (n = 14152). The IFNL4 SNP was also analyzed according to the haematological and clinical parameters of patients with COVID-19. The distributions of IFNL4 genotypes among SARS-CoV-2 positive patients [TT/TT 41.4% (n = 53), TT/ΔG 47.7% (n = 61) and ΔG/ΔG 10.9% (n = 14)] and healthy controls were comparable. Different levels of white blood cells (p = 0.036) and neutrophils (p = 0.042) were found in the IFNL4 different genotypes in patients with COVID-19; the ΔG/ΔG genotype was more represented in the groups with low white blood cells and neutrophils. There were no differences in major inflammation parameters (C-reactive protein, D-dimer, Albumin, and Lactate-dehydrogenase (LDH)] and survival rate according to the IFNL4 genotypes. In conclusion, although patients with COVID-19 did not exhibit a different distribution of the IFNL4 SNP, the ΔG/ΔG genotype was associated with a lower count of immune cell populations. These findings need to be confirmed in larger groups of patients with COVID-19 and the role of IFNL4 SNP needs to be also investigated in other respiratory viral infections.

α-adrenoceptor stimulation attenuates melanoma growth in mice

BACKGROUND AND PURPOSE

Recently, β-adrenoceptor blockade has emerged as a potential strategy to inhibit melanoma growth. However, it remains to be ascertained whether β-adrenoceptor stimulation by circulating catecholamines increases melanoma growth in mice.

EXPERIMENTAL APPROACH

B16F10 melanoma-bearing mice were used to evaluate effects of adrenaline and specific adrenoceptor (AR) ligands on tumor volume. AR expression as well as effects of AR ligands on cell viability, production of mitochondrial reactive oxygen species (mROS) and proliferation activity in B16F10 cells were determined by biochemical analyses.

KEY RESULTS

qPCR analyses revealed that B16F10 cells express both α- (α1B-, α2A- and α2B-AR) and β-ARs (β₂ -AR). We found that treatment with the α- and β-AR agonist adrenaline or with the synthetic catecholamine isoprenaline, that selectively stimulates β-ARs, did not affect melanoma growth. Conversely, adrenaline reduced tumor growth in mice co-treated with propranolol, a β1β2-AR antagonist. Adrenaline had no effect in tumor-bearing β1β2-AR knockout mice, in which β1- and β2-ARs are lacking, but it reduced tumor growth when co-administered with propranolol suggesting that tumor β2-ARs negatively regulate adrenaline antitumor activity. Additionally, we found that α1-AR stimulation with cirazoline yielded a decrease in B16F10 melanoma size. These effects on melanoma growth were paralleled by reduced cell viability and proliferation activity as well as increased mROS production in α1-AR-stimulated B16F10 cells. Decreased viability, proliferation and mitochondrial function in B16F10 cells also occurred after α2-AR stimulation by α2-AR agonist ST-91.

CONCLUSIONS AND IMPLICATIONS

In B16F10 melanoma model, stimulation of α-AR subtypes yields in vivo and in vitro anticancer activity.

Tumor-on-a-chip platforms to study cancer-immune system crosstalk in the era of immunotherapy

Immunotherapy is a powerful therapeutic approach able to re-educate the immune system to fight cancer. A key player in this process is the tumor microenvironment (TME), which is a dynamic entity characterized by a complex array of tumor and stromal cells as well as immune cell populations trafficking to the tumor site through the endothelial barrier. Recapitulating these multifaceted dynamics is critical for studying the intimate interactions between cancer and the immune system and to assess the efficacy of emerging immunotherapies, such as immune checkpoint inhibitors (ICIs) and adoptive cell-based products. Microfluidic devices offer a unique technological approach to build tumor-on-a-chip reproducing the multiple layers of complexity of cancer-immune system crosstalk. Here, we seek to review the most important biological and engineering developments of microfluidic platforms for studying cancer-immune system interactions, in both solid and hematological tumors, highlighting the role of the vascular component in immune trafficking. Emphasis is given to image processing and related algorithms for real-time monitoring and quantitative evaluation of the cellular response to microenvironmental dynamic changes. The described approaches represent a valuable tool for preclinical evaluation of immunotherapeutic strategies.

Towards a Systems Immunology Approach to Unravel Responses to Cancer Immunotherapy

Immunotherapy, particularly immune checkpoint blockade and chimeric antigen receptor (CAR)-T cells, holds a great promise against cancer. These treatments have markedly improved survival in solid as well as in hematologic tumors previously considered incurable. However, durable responses occur in a fraction of patients, and existing biomarkers (e.g. PD-L1) have shown limited prediction power. This scenario highlights the need to dissect the complex interplay between immune and tumor cells to identify reliable biomarkers of response to be used for patients’ selection. In this context, systems immunology represents indeed the new frontier to address important clinical challenges in biomarker discovery. Through the integration of multiple layers of data obtained with several high-throughput approaches, systems immunology may give insights on the vast range of inter-individual differences and on the influences of genes and factors that cooperatively shape the individual immune response to a given treatment. In this Mini Review, we give an overview of the current high-throughput methodologies, including genomics, epigenomics, transcriptomics, metabolomics, proteomics, and multi-parametric phenotyping suitable for systems immunology as well as on the key steps of data integration and biological interpretation. Additionally, we review recent studies in which multi-omics technologies have been used to characterize mechanisms of response and to identify powerful biomarkers of response to checkpoint inhibitors, CAR-T cell therapy, dendritic cell-based and peptide-based cancer vaccines. We also highlight the need of favoring the collaboration of researchers with complementary expertise and of integrating multi-omics data into biological networks with the final goal of developing accurate markers of therapeutic response.

IFN-Alpha-Mediated Differentiation of Dendritic Cells for Cancer Immunotherapy: Advances and Perspectives

The past decade has seen tremendous developments in novel cancer therapies through targeting immune-checkpoint molecules. However, since increasing the presentation of tumor antigens remains one of the major issues for eliciting a strong antitumor immune response, dendritic cells (DC) still hold a great potential for the development of cancer immunotherapy. A considerable body of evidence clearly demonstrates the importance of the interactions of type I IFN with the immune system for the generation of a durable antitumor response through its effects on DC. Actually, highly active DC can be rapidly generated from blood monocytes in vitro in the presence of IFN-α (IFN-DC), suitable for therapeutic vaccination of cancer patients. Here we review how type I IFN can promote the ex vivo differentiation of human DC and orientate DC functions towards the priming and expansion of protective antitumor immune responses. New epigenetic elements of control on activation of the type I IFN signal will be highlighted. We also review a few clinical trials exploiting IFN-DC in cancer vaccination and discuss how IFN-DC could be exploited for the design of effective strategies of cancer immunotherapy as a monotherapy or in combination with immune-checkpoint inhibitors or immunomodulatory drugs.

Type I IFN-dependent antibody response at the basis of sex dimorphism in the outcome of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the ongoing coronavirus disease 2019 (COVID-19) pandemic, induces severe pneumonia mainly in elderly males. Epidemiological data clearly indicate sex-based differences in disease outcomes, with men accounting for about 70 % of deaths, despite similar susceptibility to infection. It is well known that females are endowed with higher capacity to produce antibodies, which correlates with viral clearance and disease resolution in the context of SARS-Cov-2 infection. Many X-linked immune genes escape X inactivation showing biallelic expression in female immune cells, particularly in plasmacytoid dendritic cells (pDCs). PDCs are more active in females and endowed with high capability to induce IFN-α-mediated B cell activation and differentiation into antibody-producing plasma cells throughout epigenetic mechanisms linked to trained immunity. Thus, we hypothesize that following SARS-CoV-2 infection, epigenetic modifications of X-linked genes involved in pDC-mediated type I IFN (IFN-I) signaling occurs more effectively in females, for inducing neutralizing antibody response as an immune correlate driving sex-biased disease outcome.

Consensus guidelines for the definition, detection and interpretation of immunogenic cell death

Cells succumbing to stress via regulated cell death (RCD) can initiate an adaptive immune response associated with immunological memory, provided they display sufficient antigenicity and adjuvanticity. Moreover, multiple intracellular and microenvironmental features determine the propensity of RCD to drive adaptive immunity. Here, we provide an updated operational definition of immunogenic cell death (ICD), discuss the key factors that dictate the ability of dying cells to drive an adaptive immune response, summarize experimental assays that are currently available for the assessment of ICD in vitro and in vivo, and formulate guidelines for their interpretation.

Targeting CXCR4 potentiates anti-PD-1 efficacy modifying the tumor microenvironment and inhibiting neoplastic PD-1

Background

Inefficient T-cell access to the tumor microenvironment (TME) is among the causes of tumor immune-resistance. Previous evidence demonstrated that targeting CXCR4 improves anti-PD-1/PD-L1 efficacy reshaping TME. To evaluate the role of newly developed CXCR4 antagonists (PCT/IB2011/000120/ EP2528936B1/US2013/0079292A1) in potentiating anti-PD-1 efficacy two syngeneic murine models, the MC38 colon cancer and the B16 melanoma-human CXCR4-transduced, were employed.

Methods

Mice were subcutaneously injected with MC38 (1 × 10⁶) or B16-hCXCR4 (5 × 10⁵). After two weeks, tumors bearing mice were intraperitoneally (ip) treated with murine anti-PD-1 [RMP1–14] (5 mg/kg, twice week for 2 weeks), Pep R (2 mg/kg, 5 days per week for 2 weeks), or both agents. The TME was evaluated through immunohistochemistry and flow-cytometry. In addition, the effects of the human-anti-PD-1 nivolumab and/or Peptide-R54 (Pep R54), were evaluated on human melanoma PES43 cells and xenografts treated.

Results

The combined treatment, Pep R plus anti-PD-1, reduced the MC38 Relative Tumor Volume (RTV) by 2.67 fold (p = 0.038) while nor anti-PD-1, neither Pep R significantly impacted on tumor growth. Significant higher number of Granzyme B (GZMB) positive cells was detected in MC38 tumors from mice treated with the combined treatment (p = 0.016) while anti-PD-1 determined a modest but significant increase of tumor-infiltrating GZMB positive cells (p = 0.035). Also, a lower number of FoxP3 positive cells was detected (p = 0.022). In the B16-hCXCR4 tumors, two weeks of combined treatment reduced tumor volume by 2.27 fold while nor anti-PD-1 neither Pep R significantly impacted on tumor growth. A significant higher number of GRZB positive cells was observed in B16-hCXCR4 tumors treated with combined treatment (p = 0,0015) as compared to anti-PD-1 (p = 0.028). The combined treatment reduced CXCR4, CXCL12 and PD-L1 expression in MC38 tumors. In addition, flow cytometry on fresh B16-hCXCR4 tumors showed significantly higher Tregs number following anti-PD-1 partially reversed by the combined treatment Pep R and anti-PD-1. Combined treatment determined an increase of CD8/Tregs and CD8/MDSC ratio. To dissect the effect of anti-PD-1 and CXCR4 targeting on PD-1 expressed by human cancer cells, PES43 human melanoma xenograft model was employed. In vitro human anti-PD-1 nivolumab or pembrolizumab (10 μM) reduced PES43 cells growth while nivolumab (10 μM) inhibited pERK1/2, P38 MAPK, pAKT and p4EBP. PES43 xenograft mice were treated with Pep R54, a newly developed Pep R derivative (AcHN-Arg-Ala-[DCys-Arg- Nal(2′)-His-Pen]- COOH), plus nivolumab. After 3 weeks of combined treatment a significant reduction in tumor growth was shown (p = 0.038). PES43 lung disseminated tumor cells (DTC) were detected in fresh lung tissues as melanoma positive MCSP-APC⁺ cells. Although not statistically significant, DTC-PES43 cells were reduced in mice lungs treated with combined treatment while nivolumab or Pep R54 did not affect DTC number.

Conclusion

Combined treatment with the new developed CXCR4 antagonist, Pep R, plus anti-PD-1, reduced tumor-growth in two syngeneic murine models, anti-PD-1 sensitive and resistant, potentiating Granzyme and reducing Foxp3 cells infiltration. In addition, the human specific CXCR4 antagonist, Pep R54, cooperated with nivolumab in inhibiting the growth of the PD-1 expressing human PES43 melanoma xenograft. This evidence sheds light on PD-1 targeting mechanisms and paves the way for CXCR4/PD-1 targeting combination therapy.

The Janus Face of Tumor Microenvironment Targeted by Immunotherapy

The tumor microenvironment (TME) is a complex entity where host immune and non-immune cells establish a dynamic crosstalk with cancer cells. Through cell-cell interactions, which are mediated by key signals, such as the PD-1/PD-L1 axis, as well as the release of soluble mediators, this articulated process defines the nature of TME determining tumor development, prognosis, and response to therapy. Specifically, tumors are characterized by cellular plasticity that allows for the microenvironment to polarize towards inflammation or immunosuppression. Thus, the dynamic crosstalk among cancer, stromal, and immune components crucially favors the dominance of one of the Janus-faced contexture of TME crucial to the outcome of tumor development and therapeutic response. However, mostly, TME is dominated by an immunosuppressive landscape that blocks antitumor immunity and sustain tumor progression. Hence, in most cases, the immunosuppressive components of TME are highly competent in suppressing tumor-specific CD8⁺ T lymphocytes, the effectors of cancer destruction. In this complex context, immunotherapy aims to arm the hidden Janus face of TME disclosing and potentiating antitumor immune signals. Herein, we discuss recent knowledge on the immunosuppressive crosstalk within TME, and share perspectives on how immunotherapeutic approaches may exploit tumor immune signals to generate antitumor immunity.

Autoantibodies Specific to ERα are Involved in Tamoxifen Resistance in Hormone Receptor Positive Breast Cancer

Tamoxifen resistance is a major hurdle in the treatment of estrogen receptor (ER)-positive breast cancer. The mechanisms of tamoxifen resistance are not fully understood although several underlying molecular events have been suggested. Recently, we identified autoantibodies reacting with membrane-associated ERα (anti-ERα Abs) in sera of breast cancer patients, able to promote tumor growth. Here, we investigated whether anti-ERα Abs purified from sera of ER-positive breast cancer patients could contribute to tamoxifen resistance. Anti-ERα Abs inhibited tamoxifen-mediated effects on cell cycle and proliferation in MCF-7 cells. Moreover, anti-ERα Abs hampered the tamoxifen-mediated reduction of tumor growth in SCID mice xenografted with breast tumor. Notably, simvastatin-mediated disaggregation of lipid rafts, where membrane-associated ERα is embedded, restored tamoxifen sensitivity, preventing anti-ERα Abs effects. In conclusion, detection of serum anti-ERα Abs may help predict tamoxifen resistance and concur to appropriately inform therapeutic decisions concerning hormone therapy in ER-positive breast cancer patients.

Inflammatory cytokines associated with cancer growth induce mitochondria and cytoskeleton alterations in cardiomyocytes

Cardiac dysfunction is often observed in patients with cancer also representing a serious problem limiting chemotherapeutic intervention and even patient survival. In view of the recently established role of the immune system in the control of cancer growth, the present work has been undertaken to investigate the effects of a panel of the most important inflammatory cytokines on the integrity and function of mitochondria, as well as of the cytoskeleton, two key elements in the functioning of cardiomyocytes. Either mitochondria features or actomyosin cytoskeleton organization of in vitro‐cultured cardiomyocytes treated with different inflammatory cytokines were analyzed. In addition, to investigate the interplay between tumor growth and cardiac function in an in vivo system, immunocompetent female mice were inoculated with cancer cells and treated with the chemotherapeutic drug doxorubicin at a dosing schedule able to suppress tumor growth without inducing cardiac alterations. Analyses carried out in cardiomyocytes treated with the inflammatory cytokines, such as tumor necrosis factor α (TNF‐α), interferon γ (IFN‐γ), interleukin 6 (IL‐6), IL‐8, and IL‐1β revealed severe phenotypic changes, for example, of contractile cytoskeletal elements, mitochondrial membrane potential, mitochondrial reactive oxygen species production and mitochondria network organization. Accordingly, in immunocompetent mice, the tumor growth was accompanied by increased levels of the inflammatory cytokines TNF‐α, IFN‐γ, IL‐6, and IL‐8, either in serum or in the heart tissue, together with a significant reduction of ventricular systolic function. The alterations of mitochondria and of microfilament system of cardiomyocytes, due to the systemic inflammation associated with cancer growth, could be responsible for remote cardiac injury and impairment of systolic function observed in vivo.

Dendritic cells modulate c-kit expression on the edge between activation and death

Dendritic cells (DCs) are key players in immunity and tolerance. Some DCs express c-kit, the receptor for stem cell factor (SCF), nevertheless c-kit functional role and the regulation of its expression in DCs are incompletely defined. We recently demonstrated that autocrine SCF sustains a pro-survival circuit, and that SCF increases phospho-AKT in c-kit+ mouse bone marrow-derived DCs (BMdDCs). Herein we observed that CpG and PolyI:C, two stimuli mimicking bacterial and viral nucleic acids respectively, strongly inhibited c-kit expression by BMdDCs and spleen DCs in vitro and in vivo. Experiments in IFNARI^-/- mice showed that IFN-I pathway was required for c-kit down-regulation in cDC1s, but only partially supported it in cDC2s. Furthermore, CpG and PolyI:C strongly inhibited c-kit mRNA expression. In agreement with the reduced c-kit levels, SCF pro-survival activity was impaired. Thus in the presence of exogenously provided SCF, either PolyI:C or CpG induced spleen DC death in 2 days, while at earlier times IL-6 and IL-12 production were slightly increased. In contrast, SCF improved survival of unstimulated spleen DCs expressing high c-kit levels. Our studies suggest that c-kit down-modulation is a previously neglected component of DC response to CpG and PolyI:C, regulating DC survival and ultimately tuning immune response.

The Natural Agonist of Estrogen Receptor β Silibinin Plays an Immunosuppressive Role Representing a Potential Therapeutic Tool in Rheumatoid Arthritis

Estrogens, in particular 17β-estradiol (E2), have a strong influence on the immune system and also affect pathological conditions such as autoimmune diseases. The biological effects of E2 are mediated by two intracellular receptors, i.e., estrogen receptor (ER)α and ERβ, which function as ligand-activated nuclear transcription factors producing genomic effects. Immune cells express both ERα and ERβ that play a complex role in modulating inflammation. Phytoestrogens display estrogen-like effects. Among them, silibinin, the major active constituent of silymarin extracted by the milk thistle (Silybum marianum), has been suggested to have an ERβ selective binding. Silibinin is known to have anti-inflammatory, hepatoprotective, and anticarcinogenic effects; however, the role of silibinin in modulating human immune responses and its impact on autoimmunity remains unclear. Aim of this study was to dissect the ability of the ERβ natural ligand silibinin to modulate T cell immunity, taking into account possible differences between females and males, and to define its possible role as therapeutic tool in immune-mediated diseases. To this purpose, female and age-matched male healthy subjects and patients with active rheumatoid arthritis (RA) were recruited. We evaluated the ability of silibinin to modulate ERβ expression in T lymphocytes and its effects on T cell functions (i.e., apoptosis, proliferation, and cytokine production). We also analyzed whether silibinin was able to modulate the expression of microRNA-155 (miR-155), which strongly contributes to the pathogenesis of RA driving aberrant activation of the immune system. We demonstrated that silibinin upregulated ERβ expression, induced apoptosis, inhibited proliferation, and reduced expression of the pro-inflammatory cytokines IL-17 and TNF-α, through ERβ binding, in T lymphocytes from female and male healthy donors. We obtained similar results in T lymphocytes from patients with active RA in term of apoptosis, proliferation, and cytokine production. In addition, we found that silibinin acted as an epigenetic modifier, down-modulating the expression of miR-155. In conclusion, our data demonstrated an immunosuppressive role of silibinin, supporting its application in the treatment of autoimmune diseases as drug, but also as dietary nutritional supplement, opening new perspective in the field of autoimmune disease management.

Sexual Dimorphism of Immune Responses: A New Perspective in Cancer Immunotherapy

Nowadays, several types of tumors can benefit from the new frontier of immunotherapy, due to the recent increasing knowledge of the role of the immune system in cancer control. Among the new therapeutic strategies, there is the immune checkpoint blockade (ICB), able to restore an efficacious antitumor immunity and significantly prolong the overall survival (OS) of patients with advanced tumors such as melanoma and non-small cell lung cancer (NSCLC). Despite the impressive efficacy of these agents in some patients, treatment failure and resistance are frequently observed. In this regard, the signaling governed by IFN type I (IFN-I) has emerged as pivotal in orchestrating host defense. This pathway displays different activation between sexes, thus potentially contributing to sexual dimorphic differences in the immune responses to immunotherapy. This perspective article aims to critically consider the immune signals, with particular attention to IFN-I, that may differently affect female and male antitumor responses upon immunotherapy.

Sex disparity in cancer: roles of microRNAs and related functional players

A sexual dimorphism at the cellular level has been suggested to play a role in cancer onset and progression. In particular, very recent studies have unraveled striking differences between cells carrying XX or XY chromosomes in terms of response to stressful stimuli, indicating the presence of genetic and epigenetic differences determining sex-specific metabolic or phenotypic traits. Although this field of investigation is still in its infancy, available data suggest a key role of sexual chromosomes in determining cell life or death. In particular, cells carrying XX chromosomes exhibit a higher adaptive potential and survival behavior in response to microenvironmental variations with respect to XY cells. Cells from females also appear to be equipped with more efficient epigenetic machinery than the male counterpart. In particular, the X chromosome contains an unexpected high number of microRNAs (miRs), at present 118, in comparison with only two miRs localized on chromosome Y, and an average of 40-50 on the autosomes. The regulatory power of these small non-coding RNAs is well recognized, as 30-50% of all protein-coding genes are targeted by miRs and their role in cell fate has been well demonstrated. In addition, several further insights, including DNA methylation patterns that are different in males and females, claim for a significant gender disparity in cancer and in the immune system activity against tumors. In this brief paper, we analyze the state of the art of our knowledge on the implication of miRs encoded on sex chromosomes, and their related functional paths, in the regulation of cell homeostasis and depict possible perspectives for the epigenetic research in the field.

IFN-α potentiates the direct and immune-mediated antitumor effects of epigenetic drugs on both metastatic and stem cells of colorectal cancer

Epigenetic alterations, including dysregulated DNA methylation and histone modifications, govern the progression of colorectal cancer (CRC). Cancer cells exploit epigenetic regulation to control cellular pathways, including apoptotic and metastatic signals. Since aberrations in epigenome can be pharmacologically reversed by DNA methyltransferase and histone deacetylase inhibitors, epigenetics in combination with standard agents are currently envisaged as a new therapeutic frontier in cancer, expected to overcome drug resistance associated with current treatments. In this study, we challenged this idea and demonstrated that the combination of azacitidine and romidepsin with IFN-α owns a high therapeutic potential, targeting the most aggressive cellular components of CRC, such as metastatic cells and cancer stem cells (CSCs), via tight control of key survival and death pathways. Moreover, the antitumor efficacy of this novel pharmacological approach is associated with induction of signals of immunogenic cell death. Of note, a previously undisclosed key role of IFN-α in inducing both antiproliferative and pro-apoptotic effects on CSCs of CRC was also found. Overall, these findings open a new frontier on the suitability of IFN-α in association with epigenetics as a novel and promising therapeutic approach for CRC management.

Impaired IFN-α-mediated signal in dendritic cells differentiates active from latent tuberculosis

Individuals exposed to Mycobacterium tuberculosis (Mtb) may be infected and remain for the entire life in this condition defined as latent tuberculosis infection (LTBI) or develop active tuberculosis (TB). Among the multiple factors governing the outcome of the infection, dendritic cells (DCs) play a major role in dictating antibacterial immunity. However, current knowledge on the role of the diverse components of human DCs in shaping specific T-cell response during Mtb infection is limited. In this study, we performed a comparative evaluation of peripheral blood circulating DC subsets as well as of monocyte-derived Interferon-α DCs (IFN-DCs) from patients with active TB, subjects with LTBI and healthy donors (HD). The proportion of circulating myeloid BDCA3⁺ DCs (mDC2) and plasmacytoid CD123⁺ DCs (pDCs) declined significantly in active TB patients compared to HD, whereas the same subsets displayed a remarkable activation in LTBI subjects. Simultaneously, the differentiation of IFN-DCs from active TB patients resulted profoundly impaired compared to those from LTBI and HD individuals. Importantly, the altered developmental trait of IFN-DCs from active TB patients was associated with down-modulation of IFN-linked genes, marked changes in molecular signaling conveying antigen (Ag) presentation and full inability to induce Ag-specific T cell response. Thus, these data reveal an important role of IFN-α in determining the induction of Mtb-specific immunity.

Sexual Dimorphism of Immune Responses: A New Perspective in Cancer Immunotherapy

Nowadays, several types of tumors can benefit from the new frontier of immunotherapy, due to the recent increasing knowledge of the role of the immune system in cancer control. Among the new therapeutic strategies, there is the immune checkpoint blockade (ICB), able to restore an efficacious antitumor immunity and significantly prolong the overall survival (OS) of patients with advanced tumors such as melanoma and non-small cell lung cancer (NSCLC). Despite the impressive efficacy of these agents in some patients, treatment failure and resistance are frequently observed. In this regard, the signaling governed by IFN type I (IFN-I) has emerged as pivotal in orchestrating host defense. This pathway displays different activation between sexes, thus potentially contributing to sexual dimorphic differences in the immune responses to immunotherapy. This perspective article aims to critically consider the immune signals, with particular attention to IFN-I, that may differently affect female and male antitumor responses upon immunotherapy.

Targeting CXCR4 reverts the suppressive activity of T-regulatory cells in renal cancer

With the intent to identify biomarkers in renal cell carcinoma (RCC) the functional status of T-regulatory cells (Tregs) was investigated in primary RCC. Tregs were isolated from tumoral-(TT), peritumoral tissue-(PT) and peripheral blood-(PB) of 42 primary RCC patients and function evaluated through effector T cells (Teff) proliferation, cytokines release and demethylation of Treg Specific Region (TSDR). The highest value of Tregs was detected in TT with the uppermost amount of effector-Tregs-(CD4⁺CD25^hiFOXP3^hiCD45RA^-). PB-RCC Tregs efficiently suppress Teff proliferation compared to healthy donor (HD)-Tregs and, at the intrapatient evaluation, TT-derived Tregs were the most suppressive. Higher demethylation TSDR was detected in TT- and PB-RCC Tregs vs HD-Tregs (P <0,001). CXCR4 is highly expressed on Tregs, thus we wished to modulate Tregs function through CXCR4 inhibition. CXCR4 antagonism, elicited by a new peptidic antagonist, Peptide-R29, efficiently reversed Tregs suppression of Teff proliferation. Thus Tregs functional evaluation precisely reflects Tregs status and may be a reliable biomarker of tumoral immune response. In addition, treatment with CXCR4 antagonist, impairing Tregs function, could improve the anticancer immune response, in combination with conventional therapy and/or immunotherapy such as checkpoints inhibitors.

Antitumor Effects of Epidrug/IFNα Combination Driven by Modulated Gene Signatures in Both Colorectal Cancer and Dendritic Cells

Colorectal cancer results from the progressive accumulation of genetic and epigenetic alterations. IFN signaling defects play an important role in the carcinogenesis process, in which the inability of IFN transcription regulatory factors (IRF) to access regulatory sequences in IFN-stimulated genes (ISG) in tumors and in immune cells may be pivotal. We reported that low-dose combination of two FDA-approved epidrugs, azacytidine (A) and romidepsin (R), with IFNα2 (ARI) hampers the aggressiveness of both colorectal cancer metastatic and stem cells in vivo and triggers immunogenic cell death signals that stimulate dendritic cell (DC) function. Here, we investigated the molecular signals induced by ARI treatment and found that this drug combination increased the accessibility to regulatory sequences of ISGs and IRFs that were epigenetically silenced in both colorectal cancer cells and DCs. Likewise, specific ARI-induced histone methylation and acetylation changes marked epigenetically affected ISG promoters in both metastatic cancer cells and DCs. Analysis by ChIP-seq confirmed such ARI-induced epigenetically regulated IFN signature. The activation of this signal endowed DCs with a marked migratory capability. Our results establish a direct correlation between reexpression of silenced ISGs by epigenetic control and ARI anticancer activity and provide new knowledge for the development of innovative combined therapeutic strategies for colorectal cancer. Cancer Immunol Res; 5(7); 604-16. ©2017 AACR.

The gender perspective in cancer research and therapy: novel insights and on-going hypotheses

Cancer represents a leading cause of death whose incidence is steadily increasing worldwide due to the population aging. The Global Health Observatory of the World Health Organization reported that approximately 13% of all deaths are caused by cancer. In the 2012 the estimated total number of cancer deaths was 1.75 million, 56% in men and 44% in women. Gender is recognized to play a role in cancer incidence, progression and response to therapy. Besides anatomical and hormonal disparities, genetic differences should be considered when assessing the effects of gender on cancer. Accumulating evidence also support the existence of sex-driven differences in immune responses. Until today clinical trials and research in animal models have been gender unbalanced. In consideration of the differences between sexes observed in cancer, sex should represent an important stratification factor to be included in all randomized clinical trials for a better understanding of biological differences between men and women, which may yield improved targeted therapies.

Biphasic effects of propranolol on tumour growth in B16F10 melanoma-bearing mice

BACKGROUND AND PURPOSE

Propranolol is a vasoactive drug that shows antiangiogenic and antitumour activities in melanoma. However, it is unknown whether these activities are dose-dependent and whether there is a relationship between systemic vascular effects of propranolol and anti-melanoma activity.

EXPERIMENTAL APPROACH

Effects of increasing doses of propranolol (10, 20, 30 and 40 mg·kg^-1 ·day^-1 ) on tumour growth were studied in B16F10 melanoma-bearing mice. Histological and biochemical analyses were used to assess propranolol effects on angiogenesis and cancer cell proliferation. Systemic vascular resistance (SVR) was evaluated by measuring cardiac output and arterial BP.

KEY RESULTS

In vitro analyses revealed that B16F10 cells expressed β-adrenoceptors, but neither isoprenaline, a β-adrenoceptor agonist, nor the β-blocker propranolol affected cancer cell proliferation. In vivo studies showed that the antitumour efficacy of propranolol follows a U-shaped biphasic dose-response curve. Low doses (10 and 20 mg·kg^-1 ·day^-1 ) significantly inhibit tumour growth, whereas higher doses are progressively less effective. We also found that high-dose propranolol stimulates tumour arteriogenesis whereas no effect on angiogenesis was observed at any dose. Based on these data and considering that propranolol is a vasoactive drug, we hypothesized that it causes systemic vasoconstriction or vasodilation depending on the dose and thus alters tumour perfusion and growth. Consistent with this hypothesis, we found that propranolol has a biphasic effect on SVR with low and high doses producing vasoconstriction and vasodilation respectively.

CONCLUSIONS AND IMPLICATIONS

Propranolol inhibits melanoma growth in a U-shaped biphasic manner. A direct relationship exists between SVR and anti-melanoma activity.

New derivatives of the antimalarial drug Pyrimethamine in the control of melanoma tumor growth: an in vitro and in vivo study

Background

The antimalarial drug Pyrimethamine has been suggested to exert an antitumor activity by inducing apoptotic cell death in cancer cells, including metastatic melanoma cells. However, the dose of Pyrimethamine to be considered as an anticancer agent appears to be significantly higher than the maximum dose used as an antiprotozoal drug.

Methods

Hence, a series of Pyrimethamine analogs has been synthesized and screened for their apoptosis induction in two cultured metastatic melanoma cell lines. One of these analogs, the Methylbenzoprim, was further analyzed to evaluate cell-cycle and the mechanisms of cell death. The effects of Methylbenzoprim were also analyzed in a severe combined immunodeficiency (SCID)-mouse xenotransplantation model.

Results

Low dose of Methylbenzoprim was capable of inducing cytotoxic activity and a potent growth-inhibitory effect by arresting cell cycle in S-phase in melanoma cells. Methylbenzoprim was also detected as powerful antineoplastic agents in SCID-mouse although used at very low dose and as a single agent.

Conclusions

Our screening approach led to the identification of a “low cost” newly synthesized drug (methylbenzoprim), which is able to act as an antineoplastic agent in vitro and in vivo, inhibiting melanoma tumor growth at very low concentrations.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0409-9) contains supplementary material, which is available to authorized users.

CXCR4-antagonist Peptide R-liposomes for combined therapy against lung metastasis

The chemokine CXCL12 activates CXCR4, initiating multiple pathways that control immune cell trafficking, angiogenesis and embryogenesis; CXCR4 is also overexpressed in multiple tumors affecting metastatic dissemination. While there has been great enthusiasm for exploiting the CXCR4-CXCL12 axis as a target in cancer therapy, to date the promise has yet to be fulfilled. A new class of CXCR4-antagonist cyclic peptides was recently developed and the compound named Peptide R was identified as the most active. With the intent to improve the efficacy and biodistribution of Peptide R, stealth liposomes decorated with Peptide R were developed (PL-Peptide R). In vitro PL-Peptide R efficiently inhibited CXCR4-dependent migration and in vivo it significantly reduced lung metastases and increased overall survival in B16-CXCR4 injected C57BL/6 mice. To evaluate if PL-Peptide R could also be a drug delivery system for CXCR4 expressing tumors, the PL-Peptide R was loaded with doxorubicin (DOX) (PL-Peptide R-DOX). PL-Peptide R-DOX efficiently delivered DOX to CXCR4 expressing cell lines with a consequent decrease in the DOX IC50 efficient dose. In vivo, B16-CXCR4 injected C57BL/6 mice treated with PL-Peptide R-DOX developed fewer lung metastases compared to PL-DOX treated mice. This work provides the proof-of-concept to prevent metastasis by using combined nanomedicine.

Abstract 1656: CXCR4 antagonist-expressing liposomes reduce lung metastases and deliver drugs to CXCR4 expressing cells: a new drug-targeting device

Introduction. CXCR4 is overexpressed in multiple tumors regulating metastatic dissemination. A new class of cyclic peptides antagonist for CXCR4 receptors was recently developed1. To improve peptide efficacy and increase its delivery delivery to target cancer cells the most active antagonist, Pep R, was coupled to PEGylated liposomes (PL).

Experimental Procedures. PL conjugated to the liposomes (Lip-PepR) were prepared starting by athiolated derivative of antiCXCR4 peptides coupled to the pre-formed PL. Doxorubicin (DOX) was then encapsulated by remote loading method. Lip-PepR was evaluated through migration assay in A498 human renal cancer cell line in vitro and in an experimental animal model of pulmonary metastasis development in vivo (C57/BL mice injected with B16-CXCR4 cells and treated with 0.1 mg/kg Lipo-PepR and lipo-unconjucated i.v. twice a week for two weeks). DOX-encapsulating Lipo-PepR was evaluated in CXCR4 positive cells A498 and HT29 (human renal and colon cancer cell lines, respectivally) versus negative CXCR4 expressing cells FB-1(human anaplastic thyroid cell line), as mean cellular fluorescence. Finally, the cytotoxic effect of the lipo-DOX-PepR was examined, in A498, and HT29 cells.

Results. To evaluate the antagonistic CXCR4 function of Lipo-PepR, migration assays were conducted in A498, CXCR4 expressing cells. A498 cells were treated with the PepR or with liposome preparation (Lipo-PepR) and induced to migrate toward the CXCR4 ligand CXCL12. PepR alone inhibited cell migration such as the CXCR4 antagonist, AMD3100 while the functionalized peptide, Lipo-PepR (10µM) more efficiently inhibited migration CXCL12-induced compared. To validate the Lipo-PepR efficacy in vivo, metastases development assays were conducted. C57/BL mice were injected with murine B16-hCXCR4 melanoma cells and treated twice a week iv with Lipo-PepR versus Peptide R alone. A significant reduction in lung metastases was detected in mice treated with Lipo-Pep R even with lower dose of the Lipo-PepR (0.1mg/kg) compared to the usually used (2mg/kg). Moreover, to allow a target selective drug delivery, Lipo-PepR liposomes were loaded with doxorubicin (DOX). A CXCR4 dependent higher DOX accumulation was registered in CXCR4 positive cells, A498 and HT29 resulting in a specific higher cytotoxicity.

Conclusions. Liposomes conjugated- rationally designed CXCR4 antagonist were more efficient in inhibiting CXCR4 in vitro and in vivo. Moreover Lip-PepR loaded with a chemotherapeutic drug, such as DOX, demonstrated an enhanced drug accumulation into CXCR4 overexpressing cells.

1. Portella L et al. PLoS One. 2013 Sep 13;8(9):e74548

Citation Format: Caterina Ierano, Sara Lusa, Crescenzo D'Alterio, Giuseppina Salzano, Maria Napolitano, Maria Buoncervello, Massimo Spada, Daniele Macchia, Antonio Barbieri, Antonio Luciano, Lucia Gabriele, Giuseppe De Rosa, Stefania Scala. CXCR4 antagonist-expressing liposomes reduce lung metastases and deliver drugs to CXCR4 expressing cells: a new drug-targeting device. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1656. doi:10.1158/1538-7445.AM2014-1656

Consensus guidelines for the detection of immunogenic cell death

Apoptotic cells have long been considered as intrinsically tolerogenic or unable to elicit immune responses specific for dead cell-associated antigens. However, multiple stimuli can trigger a functionally peculiar type of apoptotic demise that does not go unnoticed by the adaptive arm of the immune system, which we named "immunogenic cell death" (ICD). ICD is preceded or accompanied by the emission of a series of immunostimulatory damage-associated molecular patterns (DAMPs) in a precise spatiotemporal configuration. Several anticancer agents that have been successfully employed in the clinic for decades, including various chemotherapeutics and radiotherapy, can elicit ICD. Moreover, defects in the components that underlie the capacity of the immune system to perceive cell death as immunogenic negatively influence disease outcome among cancer patients treated with ICD inducers. Thus, ICD has profound clinical and therapeutic implications. Unfortunately, the gold-standard approach to detect ICD relies on vaccination experiments involving immunocompetent murine models and syngeneic cancer cells, an approach that is incompatible with large screening campaigns. Here, we outline strategies conceived to detect surrogate markers of ICD in vitro and to screen large chemical libraries for putative ICD inducers, based on a high-content, high-throughput platform that we recently developed. Such a platform allows for the detection of multiple DAMPs, like cell surface-exposed calreticulin, extracellular ATP and high mobility group box 1 (HMGB1), and/or the processes that underlie their emission, such as endoplasmic reticulum stress, autophagy and necrotic plasma membrane permeabilization. We surmise that this technology will facilitate the development of next-generation anticancer regimens, which kill malignant cells and simultaneously convert them into a cancer-specific therapeutic vaccine.

Type I Interferons as Stimulators of DC-Mediated Cross-Priming: Impact on Anti-Tumor Response

Induction of potent tumor-specific cytotoxic T-cell responses is a fundamental objective in anticancer therapeutic strategies. This event requires that antigen-presenting cells present tumor-associated antigens (Ag) on their MHC class-I molecule, in a process termed cross-presentation. Dendritic cells (DC) are particularly keen on this task and can induce the cross-priming of CD8⁺ T cells, when exposed to danger or inflammatory signals that stimulate their activation. Type I interferons (IFN-I), a family of long-known immunostimulatory cytokines, have been proven to produce optimal activation signal for DC-induced cross-priming. Recent in vitro and in vivo evidences have suggested that IFN-I-stimulated cross-priming by DC against tumor-associated Ag is a key mechanism for cancer immunosurveillance and may be usefully exploited to boost anti-tumor CD8⁺ T-cell responses. Here, we will review the cross-presentation properties of different DC subsets, with special focus on cell-associated and tumor Ag, and discuss how IFN-I can modify this function, with the aim of identifying more specific and effective strategies for improving anticancer responses.

Mycobacterium tuberculosis PstS1 amplifies IFN-γ and induces IL-17/IL-22 responses by unrelated memory CD4+ T cells via dendritic cell activation

The immunological mechanisms that modulate protection during Mycobacterium tuberculosis (Mtb) infection or vaccination are not fully understood. Secretion of IFN-γ and, to a lesser extent, of IL-17 by CD4(+) T cells plays a major role both in protection and immunopathology. Few Mtb Ags interacting with DCs affect priming, activation, and regulation of Ag-unrelated CD4(+) T-cell responses. Here we demonstrate that PstS1, a 38 kDa-lipoprotein of Mtb, promotes Ag-independent activation of memory T lymphocytes specific for Ag85B or Ag85A, two immunodominant protective Ags of Mtb. PstS1 expands CD4(+) and CD8(+) memory T cells, amplifies secretion of IFN-γ and IL-22 and induces IL-17 production by effector memory cells in an Ag-unrelated manner in vitro and in vivo. These effects were mediated through the stimulation of DCs, particularly of the CD8α(-) subtype, which respond to PstS1 by undergoing phenotypic maturation and by secreting IL-6, IL-1β and, to a lower extent, IL-23. IL-6 secretion by PstS1-stimulated DCs was required for IFN-γ, and to a lesser extent for IL-22 responses by Ag85B-specific memory T cells. These results may open new perspectives for immunotherapeutic strategies to control Th1/Th17 immune responses in Mtb infections and in vaccinations against tuberculosis.

IFN-α regulates Blimp-1 expression via miR-23a and miR-125b in both monocytes-derived DC and pDC

Type I interferon (IFN-I) have emerged as crucial mediators of cellular signals controlling DC differentiation and function. Human DC differentiated from monocytes in the presence of IFN-α (IFN-α DC) show a partially mature phenotype and a special capability of stimulating CD4+ T cell and cross-priming CD8+ T cells. Likewise, plasmacytoid DC (pDC) are blood DC highly specialized in the production of IFN-α in response to viruses and other danger signals, whose functional features may be shaped by IFN-I. Here, we investigated the molecular mechanisms stimulated by IFN-α in driving human monocyte-derived DC differentiation and performed parallel studies on peripheral unstimulated and IFN-α-treated pDC. A specific miRNA signature was induced in IFN-α DC and selected miRNAs, among which miR-23a and miR-125b, proved to be negatively associated with up-modulation of Blimp-1 occurring during IFN-α-driven DC differentiation. Of note, monocyte-derived IFN-α DC and in vitro IFN-α-treated pDC shared a restricted pattern of miRNAs regulating Blimp-1 expression as well as some similar phenotypic, molecular and functional hallmarks, supporting the existence of a potential relationship between these DC populations. On the whole, these data uncover a new role of Blimp-1 in human DC differentiation driven by IFN-α and identify Blimp-1 as an IFN-α-mediated key regulator potentially accounting for shared functional features between IFN-α DC and pDC.

The dual role of IRF8 in cancer immunosurveillance

For a long time, the transcription factor interferon-regulatory factor 8 (IRF8) has been recognized as a masterpiece for the development of myeloid cells, and its role as a central regulator of immune responses has now been clarified. IRF8 is also critical for tumor progression, suggesting its fundamental relevance in multiple aspects of cancer immunosurveillance.

Interferon regulatory factor 8-deficiency determines massive neutrophil recruitment but T cell defect in fast growing granulomas during tuberculosis

Following Mycobacterium tuberculosis (Mtb) infection, immune cell recruitment in lungs is pivotal in establishing protective immunity through granuloma formation and neogenesis of lymphoid structures (LS). Interferon regulatory factor-8 (IRF-8) plays an important role in host defense against Mtb, although the mechanisms driving anti-mycobacterial immunity remain unclear. In this study, IRF-8 deficient mice (IRF-8⁻/⁻) were aerogenously infected with a low-dose Mtb Erdman virulent strain and the course of infection was compared with that induced in wild-type (WT-B6) counterparts. Tuberculosis (TB) progression was examined in both groups using pathological, microbiological and immunological parameters. Following Mtb exposure, the bacterial load in lungs and spleens progressed comparably in the two groups for two weeks, after which IRF-8⁻/⁻ mice developed a fatal acute TB whereas in WT-B6 the disease reached a chronic stage. In lungs of IRF-8⁻/⁻, uncontrolled growth of pulmonary granulomas and impaired development of LS were observed, associated with unbalanced homeostatic chemokines, progressive loss of infiltrating T lymphocytes and massive prevalence of neutrophils at late infection stages. Our data define IRF-8 as an essential factor for the maintenance of proper immune cell recruitment in granulomas and LS required to restrain Mtb infection. Moreover, IRF-8⁻/⁻ mice, relying on a common human and mouse genetic mutation linked to susceptibility/severity of mycobacterial diseases, represent a valuable model of acute TB for comparative studies with chronically-infected congenic WT-B6 for dissecting protective and pathological immune reactions.

Novel allergic asthma model demonstrates ST2-dependent dendritic cell targeting by cypress pollen

BACKGROUND

Cypress pollen causes respiratory syndromes with different grades of severity, including asthma. IL-33, its receptor ST2, and dendritic cells (DCs) have been implicated in human respiratory allergy.

OBJECTIVE

We sought to define a new mouse model of allergy to cypress pollen that recapitulates clinical parameters in allergic patients and to evaluate the implications of DCs and the IL-33/ST2 pathway in this pathology.

METHODS

BALB/c mice, either wild-type or ST2 deficient (ST2(-/-)), were sensitized and challenged with the Cupressus arizonica major allergen nCup a 1. Local and systemic allergic responses were evaluated. Pulmonary cells were characterized by means of flow cytometry. DCs were stimulated with nCup a 1 and tested for their biological response to IL-33 in coculture assays.

RESULTS

nCup a 1 causes a respiratory syndrome closely resembling human pollinosis in BALB/c mice. nCup a 1-treated mice exhibit the hallmarks of allergic pathology associated with pulmonary infiltration of eosinophils, T cells, and DCs and a dominant TH2-type immune response. IL-33 levels were increased in lungs and sera of nCup a 1-treated mice and in subjects with cypress allergy. The allergen-specific reaction was markedly reduced in ST2(-/-) mice, which showed fewer infiltrating eosinophils, T cells, and DCs in the lungs. Finally, stimulation of DCs with nCup a 1 resulted in ST2 upregulation that endowed DCs with increased ability to respond to IL-33-mediated differentiation of IL-5- and IL-13-producing CD4 T cells.

CONCLUSIONS

Our findings define a novel preclinical model of allergy to cypress pollen and provide the first evidence of a functionally relevant linkage between pollen allergens and TH2-polarizing activity by DCs through IL-33/ST2.

The tumor microenvironment: a pitch for multiple players

The cancer microenvironment may be conceptually regarded as a pitch where the main players are resident and non-resident cellular components, each covering a defined role and interconnected by a complex network of soluble mediators. The crosstalk between these cells and the tumor cells within this environment crucially determines the fate of tumor progression. Immune cells that infiltrate the tumor bed are transported there by blood circulation and exert a variety of effects, either counteracting or favoring tumor outgrowth. Here, we review and discuss the multiple populations composing the tumor bed, with special focus on immune cells subsets that positively or negatively dictate neoplastic progression. In this scenario, the contribution of cancer stem cells within the tumor microenvironment will also be discussed. Finally, we illustrate recent advances on new integrated approaches to investigate the tumor microenvironment in vitro.

Cross talk between cancer and immune cells: exploring complex dynamics in a microfluidic environment

The reconstitution of a complex microenvironment on microfluidic chips is one of the cornerstones to demonstrate the improved flexibility of these devices with respect to macroscale in vitro approaches. In this work, we realised an on-chip model to investigate the interactions between cancer and immune system. To this end, we exploited mice deficient (Knock Out, KO) for interferon regulatory factor 8 (IRF-8), a transcription factor essential for the induction of competent immune responses, to investigate how IRF-8 gene expression contributes to regulate immune and melanoma cells crosstalk. In vivo, IRF-8 KO mice are highly permissive to B16 melanoma growth due to failure of immune cells to properly exert immunosurveillance. B16 cells and immune cells isolated from the spleen of wild type (WT) and IRF-8 KO mice were co-cultured for one week in a PDMS platform and monitored by fluorescence microscopy and time-lapse recordings. We observed that WT spleen cells migrated through microchannels connecting the culturing chambers towards B16 cells and tightly interacted with tumor cells, forming clusters of activation. In contrast, IRF-8 KO immune cells poorly interacted with melanoma cells. In parallel, B16 cells were more attracted towards microchannels, acquiring a more invasive behaviour in the presence of IRF-8 KO spleen cells, with respect to WT cells. Our results strongly confirm the in vivo observations and highlight the value of on-chip co-culture systems as a useful in vitro tool to elucidate the reciprocal interactions between cancer cells and host immune system, with relevant impact in the development of more effective anti-tumor therapeutic strategies.

Type I IFNs control antigen retention and survival of CD8α(+) dendritic cells after uptake of tumor apoptotic cells leading to cross-priming

Cross-presentation is a crucial mechanism for generating CD8 T cell responses against exogenous Ags, such as dead cell-derived Ag, and is mainly fulfilled by CD8α(+) dendritic cells (DC). Apoptotic cell death occurring in steady-state conditions is largely tolerogenic, thus hampering the onset of effector CD8 T cell responses. Type I IFNs (IFN-I) have been shown to promote cross-priming of CD8 T cells against soluble or viral Ags, partly through stimulation of DC. By using UV-irradiated OVA-expressing mouse EG7 thymoma cells, we show that IFN-I promote intracellular Ag persistence in CD8α(+) DC that have engulfed apoptotic EG7 cells, regulating intracellular pH, thus enhancing cross-presentation of apoptotic EG7-derived OVA Ag by CD8α(+) DC. Notably, IFN-I also sustain the survival of Ag-bearing CD8α(+) DC by selective upmodulation of antiapoptotic genes and stimulate the activation of cross-presenting DC. The ensemble of these effects results in the induction of CD8 T cell effector response in vitro and in vivo. Overall, our data indicate that IFN-I cross-prime CD8 T cells against apoptotic cell-derived Ag both by licensing DC and by enhancing cross-presentation.

Cyclophosphamide synergizes with type I interferons through systemic dendritic cell reactivation and induction of immunogenic tumor apoptosis

Successful chemotherapy accounts for both tumor-related factors and host immune response. Compelling evidence suggests that some chemotherapeutic agents can induce an immunogenic type of cell death stimulating tumor-specific immunity. Here, we show that cyclophosphamide (CTX) exerts two types of actions relevant for the induction of antitumor immunity in vivo: (i) effect on dendritic cell (DC) homeostasis, mediated by endogenous type I interferons (IFN-I), leading to the preferential expansion of CD8α(+) DC, the main subset involved in the cross-presentation of cell-derived antigens; and (ii) induction of tumor cell death with clear-cut immunogenic features capable of stimulating tumor infiltration, engulfment of tumor apoptotic material, and CD8 T-cell cross-priming by CD8α(+) DC. Notably, the antitumor effects of CTX were efficiently amplified by IFN-I, the former providing a source of antigen and a "resetting" of the DC compartment and the latter supplying optimal costimulation for T-cell cross-priming, resulting in the induction of a strong antitumor response and tumor rejection. These results disclose new perspectives for the development of targeted and more effective chemoimmunotherapy treatments of cancer patients.

Activation of TNF receptor 2 in microglia promotes induction of anti-inflammatory pathways

Fine regulation of the innate immune response following brain injury or infection is important to avoid excessive activation of microglia and its detrimental consequences on neural cell viability and function. To get insights on the molecular networks regulating microglia activation, we analyzed expression, regulation and functional relevance of tumor necrosis factor receptors (TNFR) 2 in cultured mouse microglia. We found that microglia upregulate TNFR2 mRNA and protein and shed large amounts of soluble TNFR2, but not TNFR1, in response to pro-inflammatory stimuli and through activation of TNFR2 itself. By microarray analysis, we demonstrate that TNFR2 stimulation in microglia regulates expression of genes involved in immune processes, including molecules with anti-inflammatory and neuroprotective function like granulocyte colony-stimulating factor, adrenomedullin and IL-10. In addition, we identify IFN-γ as a regulator of the balance between pro- and anti-inflammatory/neuroprotective factors induced by TNFR2 stimulation. These data indicate that, through TNFR2, microglia may contribute to the counter-regulatory response activated in neuropathological conditions.

IFN regulatory factor-1 negatively regulates CD4+ CD25+ regulatory T cell differentiation by repressing Foxp3 expression

Regulatory T (Treg) cells are critical in inducing and maintaining tolerance. Despite progress in understanding the basis of immune tolerance, mechanisms and molecules involved in the generation of Treg cells remain poorly understood. IFN regulatory factor (IRF)-1 is a pleiotropic transcription factor implicated in the regulation of various immune processes. In this study, we report that IRF-1 negatively regulates CD4(+)CD25(+) Treg cell development and function by specifically repressing Foxp3 expression. IRF-1-deficient (IRF-1(-/-)) mice showed a selective and marked increase of highly activated and differentiated CD4(+)CD25(+)Foxp3(+) Treg cells in thymus and in all peripheral lymphoid organs. Furthermore, IRF-1(-/-) CD4(+)CD25(-) T cells showed extremely high bent to differentiate into CD4(+)CD25(+)Foxp3(+) Treg cells, whereas restoring IRF-1 expression in IRF-1(-/-) CD4(+)CD25(-) T cells impaired their differentiation into CD25(+)Foxp3(+) cells. Functionally, both isolated and TGF-beta-induced CD4(+)CD25(+) Treg cells from IRF-1(-/-) mice exhibited more increased suppressive activity than wild-type Treg cells. Such phenotype and functional characteristics were explained at a mechanistic level by the finding that IRF-1 binds a highly conserved IRF consensus element sequence (IRF-E) in the foxp3 gene promoter in vivo and negatively regulates its transcriptional activity. We conclude that IRF-1 is a key negative regulator of CD4(+)CD25(+) Treg cells through direct repression of Foxp3 expression.

The role of the interferon regulatory factor (IRF) family in dendritic cell development and function

Dendritic cells (DCs) are powerful sensors of foreign pathogens as well as cancer cells and provide the first line of defence against infection. They also serve as a major link between innate and adaptive immunity. Immature DCs respond to incoming danger signals and undergo maturation to produce high levels of proinflammatory cytokines including type I interferons (IFNs) to establish innate immunity. They then present antigens to T lymphocytes to stimulate lasting specific immune responses. Recent studies point to the importance of DCs in the induction of peripheral tolerance. Transcription factors of the IRF family have emerged as crucial controllers of many aspects of DC activity, playing an essential role in the establishment of early innate immunity. Furthermore, eight of the nine members of the IRF family have been shown to control either the differentiation and/or the functional activities of DCs. In this review, we focus on three aspects of DC properties that are under the control of IRFs: (1) the development and differentiation, (2) maturation in response to toll-like receptor (TLR) signalling and the production of anti-microbial cytokines, and (3) activation and expansion of lymphocytes to generate protective or tolerogenic immune responses.

The feedback phase of type I interferon induction in dendritic cells requires interferon regulatory factor 8

Dendritic cells (DCs) produce type I interferons (IFNs) in greater amounts than other cells, but the mechanisms remain elusive. Here we studied the role of a transcription factor, IRF8, in DC induction of type I IFNs. Upon newcastle disease virus (NDV) infection, bone marrow-derived plasmacytoid and conventional DCs induced IFN transcripts, exhibiting two-phase kinetics. The second, amplifying phase represented an IFN feedback response that accounted for much of IFN protein production. Induction of second phase transcription required IRF8. Mouse cytomegalovirus (MCMV) and Toll-like receptor-mediated IFN induction in DCs also required IRF8. Chromatin immunoprecipitation analysis showed that IRF7, IRF8, and RNA polymerase II were recruited to the IFN promoters upon stimulation. Moreover, sustained RNA polymerase II recruitment to the promoters critically depended on IRF8. Together, these data indicate that IRF8 magnifies the second phase of IFN transcription in DCs by prolonging binding of basic transcription machinery to the IFN promoters, thereby playing a role in innate immunity.