Exploring chitosan-shelled nanobubbles to improve HER2 + immunotherapy via dendritic cell targeting

Immunotherapy is a valuable approach to cancer treatment as it is able to activate the immune system. However, the curative methods currently in clinical practice, including immune checkpoint inhibitors, present some limitations. Dendritic cell vaccination has been investigated as an immunotherapeutic strategy, and nanotechnology-based delivery systems have emerged as powerful tools for improving immunotherapy and vaccine development. A number of nanodelivery systems have therefore been proposed to promote cancer immunotherapy. This work aims to design a novel immunotherapy nanoplatform for the treatment of HER2 + breast cancer, and specially tailored chitosan-shelled nanobubbles (NBs) have been developed for the delivery of a DNA vaccine. The NBs have been functionalized with anti-CD1a antibodies to target dendritic cells (DCs). The NB formulations possess dimensions of approximately 300 nm and positive surface charge, and also show good physical stability up to 6 months under storage at 4 °C. In vitro characterization has confirmed that these NBs are capable of loading DNA with good encapsulation efficiency (82%). The antiCD1a-functionalized NBs are designed to target DCs, and demonstrated the ability to induce DC activation in both human and mouse cell models, and also elicited a specific immune response that was capable of slowing tumor growth in mice in vivo. These findings are the proof of concept that loading a tumor vaccine into DC-targeted chitosan nanobubbles may become an attractive nanotechnology approach for the future immunotherapeutic treatment of cancer.

Macrophages expressing TREM-1 are involved in the progression of HPV16-related oropharyngeal squamous cell carcinoma

INTRODUCTION

Many types of research have been performed to improve the diagnosis, therapy, and prognosis of oropharyngeal carcinomas (OP-SCCs). Since they arise in lymphoid-rich areas and intense lymphocytic infiltration has been related to a better prognosis, a TREM-1 putative function in tumour progression and survival has been hypothesized.

MATERIALS AND METHODS

Twenty-seven human papillomavirus (HPV) 16+ OP-SCC specimens have been analyzed to relate TREM-1 expression with histiocytic and lymphocytic markers, HPV presence and patients' outcome.

RESULTS

No differences have been shown between intratumoral and stromal CD4+ cells, while intratumoral CD8+ lymphocytes are higher with respect to the tumour stroma (p = .0005). CD68+ cells are more than CD35+ and TREM-1+; their presence is related to CD35± and TREM-1± histiocytes (p = .005 and .026, respectively). Intratumoral CD4+ lymphocytes are higher in p16+ cases (11/27) than in p16- (p = .042); moreover, p16 positivity correlates to a better survival (p = .034). CD4+, CD8+ and CD35+ cells have no impact on survival, while CD68 expression heavily influences progression and bad outcome (p = .037). TREM-1 positivity also leads to worst overall survival (p = .001): peritumoral expression and death-cause relationship are always significant, particularly when the cause is OP-SCC (p = .000).

CONCLUSION

While p16 shows to better stratify HPV16+ patients' outcome, TREM-1+ macrophages suggest their key importance in HPV-related OP-SCCs progression.KEY MESSAGESTREM-1 positivity correlates to the worst overall survival of HPV16-positive OPSCCs-affected patients.p16-positive HPV16 related OPSCCs patients have a better prognosis with respect to p16-negative ones.

Enhanced cytotoxic effect of camptothecin nanosponges in anaplastic thyroid cancer cells in vitro and in vivo on orthotopic xenograft tumors

Anaplastic carcinoma of the thyroid (ATC) is a lethal human malignant cancer with median survival of 6 months. To date, no treatment has substantially changed its course, which makes urgent need for the development of novel drugs or novel formulations for drug delivery. Nanomedicine has enormous potential to improve the accuracy of cancer therapy by enhancing availability and stability, decreasing effective doses and reducing side effects of drugs. Camptothecin (CPT) is an inhibitor of DNA topoisomerase-I with several anticancer properties but has poor solubility and a high degradation rate. Previously, we reported that CPT encapsulated in β-cyclodextrin-nanosponges (CN-CPT) increased solubility, was protected from degradation and inhibited the growth of prostate tumor cells both in vitro and in vivo. The aim of this study was to extend that work by assessing the CN-CPT effectiveness on ATC both in vitro and in vivo. Results showed that CN-CPT significantly inhibited viability, clonogenic capacity and cell-cycle progression of ATC cell lines showing a faster and enhanced effect compared to free CPT. Moreover, CN-CPT inhibited tumor cell adhesion to vascular endothelial cells, migration, secretion of pro-angiogenic factors (IL-8 and VEGF-α), expression of β-PIX, belonging to the Rho family activators, and phosphorylation of the Erk1/2 MAPK. Finally, CN-CPT significantly inhibited the growth, the metastatization and the vascularization of orthotopic ATC xenografts in SCID/beige mice without apparent toxic effects in vivo. This work extends the previous insight showing that β-cyclodextrin-nanosponges are a promising tool for the treatment of ATC.

Regulation of Human Macrophage M1-M2 Polarization Balance by Hypoxia and the Triggering Receptor Expressed on Myeloid Cells-1

Macrophages (Mf) are a heterogeneous population of tissue-resident professional phagocytes and a major component of the leukocyte infiltrate at sites of inflammation, infection, and tumor growth. They can undergo diverse forms of activation in response to environmental factors, polarizing into specialized functional subsets. A common hallmark of the pathologic environment is represented by hypoxia. The impact of hypoxia on human Mf polarization has not been fully established. The objective of this study was to elucidate the effects of a hypoxic environment reflecting that occurring in vivo in diseased tissues on the ability of human Mf to polarize into classically activated (proinflammatory M1) and alternatively activated (anti-inflammatory M2) subsets. We present data showing that hypoxia hinders Mf polarization toward the M1 phenotype by decreasing the expression of T cell costimulatory molecules and chemokine homing receptors and the production of proinflammatory, Th1-priming cytokines typical of classical activation, while promoting their acquisition of phenotypic and secretory features of alternative activation. Furthermore, we identify the triggering receptor expressed on myeloid cells (TREM)-1, a member of the Ig-like immunoregulatory receptor family, as a hypoxia-inducible gene in Mf and demonstrate that its engagement by an agonist Ab reverses the M2-polarizing effect of hypoxia imparting a M1-skewed phenotype to Mf. Finally, we provide evidence that Mf infiltrating the inflamed hypoxic joints of children affected by oligoarticular juvenile idiopatic arthritis express high surface levels of TREM-1 associated with predominant M1 polarization and suggest the potential of this molecule in driving M1 proinflammatory reprogramming in the hypoxic synovial environment.

In Vitro and In Vivo Therapeutic Evaluation of Camptothecin-Encapsulated β-Cyclodextrin Nanosponges in Prostate Cancer

Camptothecin (CPT), a pentacyclic alkaloid, is an inhibitor of DNA Topoisomerase-I and shows a wide spectrum of anti-cancer activities. The use of CPT has been hampered by poor aqueous solubility and a high degradation rate. Previously, it has been reported that CPT encapsulated in β-cyclodextrin-nanosponges (CN-CPT) overcomes these disadvantages and improves the CPT's inhibitory effect on DU145 prostate tumor cell lines, and PC-3 growth in vitro. This work extends these observations by showing that CN-CPT significantly inhibits the adhesion and migration of these tumor cells and their STAT3 phosphorylation. The anti-adhesive effect is exerted also in human endothelial cells, in which CN-CPT also inhibits the angiogenic activity as assessed by the tubulogenesis and sprouting assays. Finally, CN-CPT substantially delays the growth of PC-3 cell engraftment in SCID mice in vivo without apparent toxic effects. These results support the use of β-cyclodextrin nanosponge nanotechnology as a potential nanocarrier for delivery of anticancer drugs in the treatment of prostate cancers.

‘Hypoxia reprograms human macrophages towards a proinflammatory direction’

Mononuclear phagocytes are recruited from the circulation as primary monocytes to sites of infection, inflammation, and tumor growth, where they undergo terminal differentiation into macrophages. Macrophages can be polarized into classically activated macrophages (M1) or alternatively activated macrophages (M2) which are characterized by a proinflammatory or an anti-inflammatory phenotype, respectively. M1 and M2 polarization is regulated by microenvironment factors. A common feature of pathologic situations is represented by hypoxia. Little is known about the impact of hypoxia on M1/M2 polarization. To address this issue, M1 (CD80+) and M2 (CD206+) macrophages were generated by culturing human monocytes with LPS or IL4 for 24h under normoxia (20%O2) or hypoxia (1%O2). We show that hypoxia amplifies the proinflammatory state of M1 macrophages and reprograms M2 macrophages towards a proinflammatory direction by increasing the production of inflammatory and proangiogenic cytokines/chemokines. The hypoxic pathologic microenvironment can tune the expression of immunoregulatory signaling receptors, whose deregulated expression may result in amplification of inflammation or establishment of immune escape situations. We demonstrate that hypoxia strongly upregulates the expression of one of such receptors, TREM -1, in M1 and M2 macrophages. Engagement of TREM-1 by agonist Ab triggers further production of M1-type cytokines/chemokines in both populations. These results suggest the role of the hypoxic environment present at pathologic sites in skewing macrophages towards a M1-like proinflammatory phenotype by inducing TREM-1, highlighting the potential of targeting TREM-1 in inflammatory disorders and in tumors.

Regulation of Langerhans cell functions in a hypoxic environment

Langerhans cells (LCs) are a specialized dendritic cell subset that resides in the epidermis and mucosal epithelia and is critical for the orchestration of skin immunity. Recent evidence suggest that LCs are involved in aberrant wound healing and in the development of hypertrophic scars and chronic wounds, which are characterized by a hypoxic environment. Understanding LCs biology under hypoxia may, thus, lead to the identification of novel pathogenetic mechanisms of wound repair disorders and open new therapeutic opportunities to improve wound healing. In this study, we characterize a previously unrecognized role for hypoxia in significantly affecting the phenotype and functional properties of human monocyte-derived LCs, impairing their ability to stimulate naive T cell responses, and identify the triggering receptor expressed on myeloid (TREM)-1, a member of the Ig immunoregulatory receptor family, as a new hypoxia-inducible gene in LCs and an activator of their proinflammatory and Th1-polarizing functions in a hypoxic environment. Furthermore, we provide the first evidence of TREM-1 expression in vivo in LCs infiltrating hypoxic areas of active hypertrophic scars and decubitous ulcers, pointing to a potential pathogenic role of this molecule in wound repair disorders.

KEY MESSAGES

Hypoxia modulates surface molecule expression and cytokine profile in Langerhans cells. Hypoxia impairs human Langerhans cell stimulatory activity on naive T cells. Hypoxia selectively induces TREM-1 expression in human Langerhans cells. TREM-1 engagement stimulates Langerhans cell inflammatory and Th1-polarizing activity. TREM-1 is expressed in vivo in Langerhans cells infiltrating hypoxic skin lesions.

Human mesenchymal stem cells and derived extracellular vesicles induce regulatory dendritic cells in type 1 diabetic patients

AIMS/HYPOTHESIS

Mesenchymal stem cells (MSCs) can exert an immunosuppressive effect on any component of the immune system, including dendritic cells (DCs), by direct contact, the release of soluble markers and extracellular vesicles (EVs). We evaluated whether MSCs and MSC-derived EVs have an immunomodulatory effect on monocyte-derived DCs in type 1 diabetes.

METHODS

Bone marrow derived MSCs were characterised and EVs were obtained by ultracentrifugation. DCs were differentiated from CD14(+) cells, obtained from nine type 1 diabetic patients at disease onset, pulsed with antigen GAD65 and cultured with MSCs or EVs. Levels of DC maturation and activation markers were evaluated by flow cytometry. GAD65-pulsed DCs and autologous CD14(-) cell were co-cultured and IFN-γ enzyme-linked immunosorbent spot responses were assayed. Secreted cytokine levels were measured and Th17 and regulatory T cells were analysed.

RESULTS

MSC- and EV-conditioned DCs acquired an immature phenotype with reduced levels of activation markers and increased IL-10 and IL-6 production. Conditioned DC plus T cell co-cultures showed significantly decreased IFN-γ spots and secretion levels. Moreover, higher levels of TGF-β, IL-10 and IL-6 were detected compared with unconditioned DC plus T cell co-cultures. Conditioned DCs decreased Th17 cell numbers and IL-17 levels, and increased FOXP3(+) regulatory T cell numbers. EVs were internalised by DCs and EV-conditioned DCs exhibited a similar effect.

CONCLUSIONS/INTERPRETATION

In type 1 diabetes, MSCs induce immature IL-10-secreting DCs in vitro, thus potentially intercepting the priming and amplification of autoreactive T cells in tissue inflammation. These DCs can contribute to the inhibition of inflammatory T cell responses to islet antigens and the promotion of the anti-inflammatory, regulatory responses exerted by MSCs.

Anti-α-enolase antibody limits the invasion of myeloid-derived suppressor cells and attenuates their restraining effector T cell response

Pancreatic Ductal Adenocarcinoma (PDA) is a very aggressive tumor for which effective therapeutical strategies are still lacking. Globally, the 5 y survival rate is 5-7% and surgery is the only potentially curative treatment. Immunotherapy represents a novel possibility for treating PDA, and myeloid-derived suppressor cells (MDSC), which are increased in cancer patients and correlate with metastatic burden and cancer stage, offer a new target in cancer therapy. We have previously shown that antibodies against the PDA-associated antigen α-enolase (ENO1) are detected in more than 60% of PDA patients and correlate with a better prognosis. Furthermore, ENO1-DNA vaccination in mice induced anti-ENO1 antibodies that mediated antitumor activity. In this study, the effects of anti-ENO1 binding on MDSC functions and on the T cell response were evaluated. Here, we show that MDSC express ENO1 on their surface, which increased after LPS stimulation. Moreover, anti-ENO1 mAb inhibited adhesion to endothelial cells, as well as in vitro and in vivo migration. Similarly, after ENO1 mAb treatment of MDSC, arginase activity decreased, while the secretion of pro-inflammatory cytokines (particularly IL-6) increased, and co-stimulatory molecule expression and suppression functions were only partially affected. Finally, we found that activated T cells in the presence of anti-ENO1 mAb-treated MDSC increased IFNγ and IL-17 secretion and decreased IL-10 and TGFβ secretion compared to control MDSC. In conclusion, anti-ENO1 antibodies may inhibit in vivo the infiltration into the tumor microenvironment of MDSC, and attenuate their restraining of effector T cell response, opening a new perspective to render PDA immunotherapy more effective.

Abstract 1294: Identification of tumor-specific antigens associated with RET/PTC3 expression

Relocated in transformation/papillary thyroid carcinoma, RET/PTC3 (RP3) is a fusion oncogene that causes a form of papillary thyroid cancer (PTC). In addition to driving transformation, the constitutively active kinase precociously phosphorylates itself as well as other intracellular proteins, thereby providing tumor-specific targets for the adaptive immune system.

PTCs are known to have the ability to escape the immune system driving a dysregulation of the activity of several cell populations involved in the immune response. Indeed we found that mice immunized with RP3+/MHC class II+ cells produce dramatically fewer IFNg-secreting CD4+ T cells compared to mice immunized with RP3-/MHC class II+ counterparts as measured in the spleens.

We demonstrated the immunogenicity of RP3 with reactivity in both BALB/c and C57BL/6 mice to RP3/IEd- and RP3/CIITA-expressing cells. Also, we observed immunogenicity of RP3-derived phosphopeptides in ELISpot assays, supporting the hypothesis that the aberrant autophosphorylation of RP3 is a source of tumor-specific immunogenicity.

Finally, utilizing a RP3-expressing vaccinia vector for immunization of C57BL/6 mice, we identified peptide sequences that appear to be immunogenic on the basis of unique conformation of the fusion protein that impacts antigen processing.

Taken together these results could pave the way for better vaccine approaches without accompanying autoimmunity.

Citation Format: Laura Sponton, Gabriela Cosma, Mark Mendonca, Mirella Giovarelli, Laurence Crane Eisenlohr. Identification of tumor-specific antigens associated with RET/PTC3 expression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1294. doi:10.1158/1538-7445.AM2015-1294

Solid lipid nanoparticles of cholesteryl butyrate inhibit the proliferation of cancer cells in vitro and in vivo models

BACKGROUND AND PURPOSE

Solid lipid nanoparticles containing cholesteryl butyrate (cholbut SLN) can be a delivery system for the anti-cancer drug butyrate. These nanoparticles inhibit adhesion of polymorphonuclear and tumour cells to endothelial cells and migration of tumour cells, suggesting that they may act as anti-inflammatory and anti-tumour agents. Here we have evaluated the effects of cholbut SLN on tumour cell growth using in vitro and in vivo models.

EXPERIMENTAL APPROACH

Cholbut SLNs were incubated with cultures of four tumour cell lines, and cell growth was analysed by assessing viability, clonogenic capacity and cell cycle. Effects on intracellular signalling was assessed by Western blot analysis of Akt expression. The in vivo anti-tumour activity was measured in two models of PC-3 cell xenografts in SCID/Beige mice.

KEY RESULTS

Cholbut SLN inhibited tumour cell line viability, clonogenic activity, Akt phosphorylation and cell cycle progression. In mice injected i.v. with PC3-Luc cells and treated with cholbut SLN, . in vivo optical imaging and histological analysis showed no metastases in the lungs of the treated mice. In another set of mice injected s.c. with PC-3 cells and treated with cholbut SLN when the tumour diameter reached 2 mm, analysis of the tumour dimensions showed that treatment with cholbut SLN substantially delayed tumour growth.

CONCLUSION AND IMPLICATIONS

Cholbut SLN were effective in inhibiting tumour growth in vitro and in vivo. These effects may involve, in part, inhibition of Akt phosphorylation, which adds another mechanism to the activity of this multipotent drug.

Human mesenchymal stem cell-derived microvesicles modulate T cell response to islet antigen glutamic acid decarboxylase in patients with type 1 diabetes

AIMS/HYPOTHESIS

Mesenchymal stem cells (MSCs) have been shown to abrogate in vitro the proinflammatory response in type 1 diabetes. The mechanism involves paracrine factors, which may include microvesicles (MVs). We evaluated whether MVs derived from heterologous bone-marrow MSCs exert an immunomodulatory effect on T cell responses against GAD (glutamic acid decarboxylase) antigen in type 1 diabetes.

METHODS

MVs were purified from heterologous human MSCs by differential centrifugation. Peripheral blood mononuclear cells (PBMCs) were obtained from patients with type 1 diabetes at disease onset, and responses to GAD65 stimulation were assessed by IFN-γ enzyme-linked immunosorbent spot analysis. Levels of cytokines and prostaglandin E2 (PGE2) were measured in the supernatant fraction, and T helper 17 (Th17) and regulatory T cell analysis was performed.

RESULTS

MVs were internalised by PBMCs, as assessed by confocal microscopy and flow cytometry analyses. MVs significantly decreased IFN-γ spots and levels in GAD65-stimulated PBMCs, and significantly increased transforming growth factor-β (TGF-β), IL-10, IL-6 and PGE2 levels. Furthermore, MVs decreased the number of Th17 cells and the levels of IL-17, and increased FoxP3(+) regulatory T cells in GAD65-stimulated PBMCs.

CONCLUSIONS/INTERPRETATION

These results provide evidence that MSC-derived MVs can inhibit in vitro a proinflammatory response to an islet antigenic stimulus in type 1 diabetes. The action of MVs involves PGE2 and TGF-β signalling pathways and IL-10 secretion, suggesting a switch to an anti-inflammatory response of T cells.

Chimeric rat/human HER2 efficiently circumvents HER2 tolerance in cancer patients

PURPOSE

Despite the great success of HER2 vaccine strategies in animal models, effective clinical results have not yet been obtained. We studied the feasibility of using DNA coding for chimeric rat/human HER2 as a tool to break the unresponsiveness of T cells from patients with HER2-overexpressing tumors (HER2-CP).

EXPERIMENTAL DESIGN

Dendritic cells (DCs) generated from patients with HER2-overexpressing breast (n = 28) and pancreatic (n = 16) cancer were transfected with DNA plasmids that express human HER2 or heterologous rat sequences in separate plasmids or as chimeric constructs encoding rat/human HER2 fusion proteins and used to activate autologous T cells. Activation was evaluated by IFN-γ ELISPOT assay, perforin expression, and ability to halt HER2+ tumor growth in vivo.

RESULTS

Specific sustained proliferation and IFN-γ production by CD4 and CD8 T cells from HER2-CP was observed after stimulation with autologous DCs transfected with chimeric rat/human HER2 plasmids. Instead, T cells from healthy donors (n = 22) could be easily stimulated with autologous DCs transfected with any human, rat, or chimeric rat/human HER2 plasmid. Chimeric HER2-transfected DCs from HER2-CP were also able to induce a sustained T-cell response that significantly hindered the in vivo growth of HER2(+) tumors. The efficacy of chimeric plasmids in overcoming tumor-induced T-cell dysfunction relies on their ability to circumvent suppressor effects exerted by regulatory T cells (Treg) and/or interleukin (IL)-10 and TGF-β1.

CONCLUSIONS

These results provide the proof of concept that chimeric rat/human HER2 plasmids can be used as effective vaccines for any HER2-CP with the advantage of being not limited to specific MHC. Clin Cancer Res; 20(11); 2910-21. ©2014 AACR.

Vaccination with ENO1 DNA prolongs survival of genetically engineered mice with pancreatic cancer

BACKGROUND & AIMS

Pancreatic ductal adenocarcinoma (PDA) is an aggressive tumor, and patients typically present with late-stage disease; rates of 5-year survival after pancreaticoduodenectomy are low. Antibodies against α-enolase (ENO1), a glycolytic enzyme, are detected in more than 60% of patients with PDA, and ENO1-specific T cells inhibit the growth of human pancreatic xenograft tumors in mice. We investigated whether an ENO1 DNA vaccine elicits antitumor immune responses and prolongs survival of mice that spontaneously develop autochthonous, lethal pancreatic carcinomas.

METHODS

We injected and electroporated a plasmid encoding ENO1 (or a control plasmid) into Kras(G12D)/Cre (KC) mice and Kras(G12D)/Trp53(R172H)/Cre (KPC) mice at 4 weeks of age (when pancreatic intraepithelial lesions are histologically evident). Antitumor humoral and cellular responses were analyzed by histology, immunohistochemistry, enzyme-linked immunosorbent assays, flow cytometry, and enzyme-linked immunosorbent spot and cytotoxicity assays. Survival was analyzed by Kaplan-Meier analysis.

RESULTS

The ENO1 vaccine induced antibody and a cellular response and increased survival times by a median of 138 days in KC mice and 42 days in KPC mice compared with mice given the control vector. On histologic analysis, the vaccine appeared to slow tumor progression. The vaccinated mice had increased serum levels of anti-ENO1 immunoglobulin G, which bound the surface of carcinoma cells and induced complement-dependent cytotoxicity. ENO1 vaccination reduced numbers of myeloid-derived suppressor cells and T-regulatory cells and increased T-helper 1 and 17 responses.

CONCLUSIONS

In a genetic model of pancreatic carcinoma, vaccination with ENO1 DNA elicits humoral and cellular immune responses against tumors, delays tumor progression, and significantly extends survival. This vaccination strategy might be developed as a neoadjuvant therapy for patients with PDA.

Pro-inflammatory profile of preeclamptic placental mesenchymal stromal cells: new insights into the etiopathogenesis of preeclampsia

The objective of the present study was to evaluate whether placental mesenchymal stromal cells (PDMSCs) derived from normal and preeclamptic (PE) chorionic villous tissue presented differences in their cytokines expression profiles. Moreover, we investigated the effects of conditioned media from normal and PE-PDMSCs on the expression of pro-inflammatory Macrophage migration Inhibitory Factor (MIF), Vascular Endothelial Growth Factor (VEGF), soluble FMS-like tyrosine kinase-1 (sFlt-1) and free β-human Chorionic Gonadotropin (βhCG) by normal term villous explants. This information will help to understand whether anomalies in PE-PDMSCs could cause or contribute to the anomalies typical of preeclampsia.

METHODS

Chorionic villous PDMSCs were isolated from severe preeclamptic (n = 12) and physiological control term (n = 12) placentae. Control and PE-PDMSCs's cytokines expression profiles were determined by Cytokine Array. Control and PE-PDMSCs were plated for 72 h and conditioned media (CM) was collected. Physiological villous explants (n = 48) were treated with control or PE-PDMSCs CM for 72 h and processed for mRNA and protein isolation. MIF, VEGF and sFlt-1 mRNA and protein expression were analyzed by Real Time PCR and Western Blot respectively. Free βhCG was assessed by immunofluorescent.

RESULTS

Cytokine array showed increased release of pro-inflammatory cytokines by PE relative to control PDMSCs. Physiological explants treated with PE-PDMSCs CM showed significantly increased MIF and sFlt-1 expression relative to untreated and control PDMSCs CM explants. Interestingly, both control and PE-PDMSCs media induced VEGF mRNA increase while only normal PDMSCs media promoted VEGF protein accumulation. PE-PDMSCs CM explants released significantly increased amounts of free βhCG relative to normal PDMSCs CM ones.

CONCLUSIONS

Herein, we reported elevated production of pro-inflammatory cytokines by PE-PDMSCs. Importantly, PE PDMSCs induced a PE-like phenotype in physiological villous explants. Our data clearly depict chorionic mesenchymal stromal cells as central players in placental physiopathology, thus opening to new intriguing perspectives for the treatment of human placental-related disorders as preeclampsia.

Chronic hypoxia reprograms human immature dendritic cells by inducing a proinflammatory phenotype and TREM-1 expression

DCs are powerful antigen-presenting cells central in the orchestration of innate and acquired immunity. DC development, migration, and activities are intrinsically linked to the microenvironment. DCs migrate through pathologic tissues before reaching their final destination in the lymph nodes. Hypoxia, a condition of low partial oxygen pressure, is a common feature of many pathologic situations, capable of modifying DC phenotype and functional behavior. We studied human monocyte-derived immature DCs generated under chronic hypoxic conditions (H-iDCs). We demonstrate by gene expression profiling the upregulation of a cluster of genes coding for antigen-presentation, immunoregulatory, and pattern recognition receptors, suggesting a stimulatory role for hypoxia on iDC immunoregulatory functions. In particular, we show that H-iDCs express triggering receptor expressed on myeloid cells(TREM-1), a member of the Ig superfamily of immunoreceptors and an amplifier of inflammation. This effect is reversible because H-iDC reoxygenation results in TREM-1 down-modulation. TREM-1 engagement promotes upregulation of T-cell costimulatory molecules and homing chemokine receptors, typical of mature DCs, and increases the production of proinflammatory, Th1/Th17-priming cytokines/chemokines, resulting in increased T-cell responses. These results suggest that TREM-1 induction by the hypoxic microenvironment represents a mechanism of regulation of Th1-cell trafficking and activation by iDCs differentiated at pathologic sites.

Triggering of B7h by the ICOS modulates maturation and migration of monocyte-derived dendritic cells

B7h, expressed by several cell types, binds ICOS expressed by activated T cells. We have previously shown that B7h triggering by ICOS-Fc inhibits human endothelial cell adhesiveness. This work investigated the effect of ICOS-Fc on human monocyte-derived dendritic cells (DCs). We found that DCs matured with LPS in the presence of ICOS-Fc (mDCs(ICOS)) produced greater amounts of IL-23 and IL-10, and promoted a higher secretion of IL-17A and IL-17F in MLCs than did those DCs matured with LPS alone (mDCs). Moreover, mDCs(ICOS) pulsed with the keyhole limpet hemocyanin Ag during the maturation phase were better stimulators of Ag-specific MHC class I-, but not class II-restricted T cells than mDCs. This was probably due to promotion of cross-presentation because it was not detected when the Flu-MA(58-66) Ag was directly loaded on already matured DCs and mDCs(ICOS). Finally, ICOS-Fc inhibited the adhesion of both immature DCs and mDCs to vascular and lymphoid endothelial cells, their migratory activity, and the expression of the Rac-1 activator β-Pix involved in cell motility. These data suggest that B7h stimulation modulates DC function with effects on their maturation and recruitment into tissues. This opens a novel view on the use of interactors of the ICOS:B7h system as immunomodulatory drugs.

The hypoxic environment reprograms the cytokine/chemokine expression profile of human mature dendritic cells

Myeloid dendritic cells (DCs) are professional antigen-presenting cells critical for the orchestration of immunity and maintenance of self-tolerance. DC development and functions are tightly regulated by a complex network of inhibitory and activating signals present in the tissue microenvironment, and dysregulated DC responses may result in amplification of inflammation, loss of tolerance, or establishment of immune escape mechanisms. Generation of mature (m)DCs from monocytic precursors recruited at pathological sites occurs under condition of low partial oxygen pressure (pO(2)). However, the way in which the hypoxic microenvironment modulates the functions of these cells is still not clear. We demonstrate that chronic hypoxia (4 days, 1% O(2)) promotes the onset of a highly proinflammatory gene expression profile in mDCs generated from primary human monocytes, characterized by the modulation of a significant cluster of genes coding for proinflammatory chemokines/cytokines and/or their receptors. Within the chemokine system, strong upregulation of genes encoding proteins chemotactic for neutrophils, such as CXCL2, CXCL3, CXCL5, CXCL6, and CXCL8, and for activated/memory T lymphocytes, monocytes, and immature (i) DCs, e.g. CCL20, CCL3 and CCL5, was observed, concomitant with decreased expression of genes coding for naive/resting T cells chemoattractants, CCL18 and CCL23. Other hypoxia-inducible genes coded for cytokines with a primary role in inflammation and angiogenesis, including osteopontin, vascular endothelial growth factor, and IL-1β. mRNA modulation was paralleled by protein secretion. These results suggest that conditions of reduced O(2) availability reprograms mDCs toward a proinflammatory direction by tuning the cytokine/chemokine repertoire, thus affecting their ability to regulate leukocyte trafficking and activation at pathological sites, with potential implications for the pathogenesis of chronic inflammatory diseases.

PI3K/AKT signaling determines a dynamic switch between distinct KSRP functions favoring skeletal myogenesis

Skeletal myogenesis is orchestrated by distinct regulatory signaling pathways, including PI3K/AKT, that ultimately control muscle gene expression. Recently discovered myogenic micro-RNAs (miRNAs) are deeply implicated in muscle biology. Processing of miRNAs from their primary transcripts is emerging as a major step in the control of miRNA levels and might be well suited to be regulated by extracellular signals. Here we report that the RNA binding protein KSRP is required for the correct processing of primary myogenic miRNAs upon PI3K/AKT activation in myoblasts C2C12 and in the course of injury-induced muscle regeneration, as revealed by Ksrp knock-out mice analysis. PI3K/AKT activation regulates in opposite ways two distinct KSRP functions inhibiting its ability to promote decay of myogenin mRNA and activating its ability to favor maturation of myogenic miRNAs. This dynamic regulatory switch eventually contributes to the activation of the myogenic program.

Expression of IFNγR2 mutated in a dileucine internalization motif reinstates IFNγ signaling and apoptosis in human T lymphocytes

In T lymphocytes, the internalization of the R2 chain of the IFN-γ receptor (IFN-γR2) prevents the switching-on of pro-apoptotic and anti-proliferative genes induced by the IFN-γ/STAT1 pathway. In fibroblasts, a critical role of controlling the IFN-γR2 internalization is played by the LI(255-256) intracellular motif. Here we show that, in human malignant T cells, the expression of a mutated IFN-γR2 chain in which the LI(255-256) internalization motif is replaced by two alanines (LI(255-256)AA) induces cell surface accumulation of the receptor and reinstates the cell sensitivity to IFN-γ. In comparison with T cells that expressed wild-type IFN-γR2, cells that expressed the mutated receptor displayed, in response to IFN-γ a sustained activation of STAT1. The activation of this signaling pathway leads to higher induction of MHC class I and FasL expression and triggered apoptosis. Malignant ST4 cells transduced with either wild-type or mutated receptor were able to grow in SCID mice, but only the proliferation of T cells expressing the mutated receptor was inhibited by IFN-γ. Finally, lentiviral-mediated transduction of the mutated receptor in T lymphoblasts from healthy donors reinstated their IFN-γ-dependent apoptosis. As a whole, these data indicate that perturbation of IFN-γR2 internalization by mutating the LI(255-256) motif induces a timely coordinated activation of IFN-γ/STAT1 signaling pathways that leads to the apoptosis of T cells.

Human mesenchymal stem cells modulate cellular immune response to islet antigen glutamic acid decarboxylase in type 1 diabetes

CONTEXT

Mesenchymal stem cells (MSCs) exert an immunosuppressive effect on the immune system. However, studies on the immunomodulatory potential of MSCs in type 1 diabetes are lacking.

OBJECTIVE

We aimed to evaluate whether human MSCs may inhibit in vitro pancreatic islet antigen-specific T cell activation in type 1 diabetes.

DESIGN

Human MSCs were isolated and characterized. Peripheral blood mononuclear cells (PBMCs) were obtained from nine type 1 diabetic patients at disease onset and 13 healthy control subjects. IFN-gamma, IL-10, and IL-4 enzyme-linked immunospot responses of lymphocytes incubated with glutamic acid decarboxylase 65 (GAD65) were investigated in PBMC cultures and PBMC/MSC cocultures. Levels of prostaglandin E2 (PGE2), IFN-gamma, IL-4, and IL-10 in supernatants were measured by ELISA. PGE2 inhibition experiments with NS-398 and indomethacin were also performed.

RESULTS

Five diabetic patients were identified with a positive PBMC IFN-gamma response to GAD65 and negative IL-10 and IL-4 response. PBMC/MSC cocultures resulted in a significant decrease in the number of spots and in detection of IL-4-secreting cells. PGE2 inhibitors abrogated the immune-suppressive effect, indicating an involvement of PGE2 production, and the constitutive production of PGE2 by MSCs was enhanced in PBMC/MSC coculture. Moreover, in GAD-responder patients, GAD-stimulated PBMC/MSC cocultures significantly decreased secretion of IFN-gamma and IL-10 and increased secretion of IL-4.

CONCLUSIONS

These results provide evidence that human MSCs abrogate in vitro a proinflammatory T helper type 1 response to an islet antigenic stimulus in type 1 diabetes. MSCs induce IL-4-producing cells, suggesting a possible switch to an antiinflammatory T helper type 2 signaling of T cells.

Circulating autoantibodies to phosphorylated α-enolase are a hallmark of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis and no diagnostic markers have, as of yet, been defined. In PDAC patients, α-enolase (ENOA) is up-regulated and elicits the production of autoantibodies. Here, we analyzed the autoantibody response to post-translational modifications of ENOA in PDAC patients. ENOA isolated from PDAC tissues and cell lines was characterized by two-dimensional electrophoresis (2-DE) Western blot (WB), revealing the expression of six different isoforms (named ENOA1,2,3,4,5,6) whereas only 4 isoforms (ENOA3,4,5,6) were detectable in normal tissues. As assessed by 2-DE WB, 62% of PDAC patients produced autoantibodies to the two more acidic isoforms (ENOA1,2) as opposed to only 4% of controls. Mass spectrometry showed that ENOA1,2 isoforms were phosphorylated on serine 419. ROC analysis demonstrated that autoantibodies to ENOA1,2 usefully complement the diagnostic performance of serum CA19.9 levels, achieving approximately 95% diagnostic accuracy in both advanced and resectable PDAC. Moreover, the presence of autoantibodies against ENOA1,2 correlated with a significantly better clinical outcome in advanced patients treated with standard chemotherapy. In conclusion, our results demonstrate that ENOA phosphorylation is associated with PDAC and induces specific autoantibody production in PDAC patients that may have diagnostic value.

The hypoxic microenvironment modulates monocytic and dendritic cell inflammatory gene expression (133.10)

Hypoxia is a condition of low oxygen tension occurring in inflammatory lesions which creates a special microenvironment conditioning cell physiology. We investigated the molecular bases underlying the immunoregulatory functions of monocytes (Mn) and of terminally differentiated dendritic cells (mDCs) within the hypoxic microenvironment both in vitro and in vivo. Mn and mDCs hypoxic transcriptome was assessed using high-density oligonucleotide microarrays. The molecular pathways underlying gene transcription regulation by hypoxia were evaluated by promoter-driven reporter studies and EMSA. Profound modulation of the gene expression pattern was detected following Mn and DC exposure to 1% O2. We identified a significant cluster of hypoxia-responsive genes with immunological relevance, among which the macrophage inflammatory protein-3α (MIP-3α/CCL20) and the cytokine/extracellular matrix protein, osteopontin (OPN). Hypoxic upregulation of both genes was confirmed in vitro in primary Mn, Mn-derived macrophages, and DCs and in vivo in Mn cell recruited to the synovial joints of patients affected by Juvenile Idiopatic Arthritis (JIA), and associated with hypoxia-inducible factor-1α (HIF-1α) expression and NF-kB transcriptional activation. These studies lead to new perspectives on the impact of hypoxia on mononuclear phagocyte functions and to the definition of the mechanisms linking low pO2 to the pathogenesis of chronic inflammation.

Survival and migration of human dendritic cells are regulated by an IFN-alpha-inducible Axl/Gas6 pathway

Axl, a prototypic member of the transmembrane tyrosine kinase receptor family, is known to regulate innate immunity. In this study, we show that Axl expression is induced by IFN-alpha during human dendritic cell (DC) differentiation from monocytes (IFN/DC) and that constitutively Axl-negative, IL-4-differentiated DC (IL-4/DC) can be induced to up-regulate Axl by IFN-alpha. This effect is inhibited by TLR-dependent maturation stimuli such as LPS, poly(I:C), TLR7/8 ligand, and CD40L. LPS-induced Axl down-regulation on the surface of human IFN-alpha-treated DC correlates with an increased proteolytic cleavage of Axl and with elevated levels of its soluble form. GM6001 and TAPI-1, general inhibitors of MMP and ADAM family proteases, restored Axl expression on the DC surface and diminished Axl shedding. Furthermore, stimulation of Axl by its ligand, Gas6, induced chemotaxis of human DC and rescued them from growth factor deprivation-induced apoptosis. Our study provides the first evidence that Gas6/Axl-mediated signaling regulates human DC activities, and identifies Gas6/Axl as a new DC chemotaxis pathway. This encourages one to explore whether dysregulation of this novel pathway in human DC biology is involved in autoimmunity characterized by high levels of IFN-alpha.

IL-6, but not IFN-gamma, triggers apoptosis and inhibits in vivo growth of human malignant T cells on STAT3 silencing

STAT1 and STAT3 are the main mediators of the signaling of interferons (IFNs) and of gp130 cytokines, respectively. Neoplastic T lymphocytes frequently become resistant to the IFN-gamma/STAT1 apoptotic pathway, often because of the downregulation of the IFN-gammaR2 receptor chain. Many studies suggest that cross-regulation between different STATs, in particular between STAT1 and STAT3, may profoundly affect cytokine/growth factor signaling. Here, the function of STAT3 in the negative regulation of STAT1 apoptotic pathway was investigated by RNA interference-mediated STAT3 silencing in human malignant T lymphocytes. In STAT3-depleted cells, interleukin (IL)-6 acquired the capacity to induce apoptosis, correlating with prolonged STAT1 activation and the induction of major histocompatibility complex (MHC) class I expression. In contrast, in the absence of STAT3, IFN-gamma could slightly enhance apoptosis but its ability to induce MHC class I expression was unchanged. Accordingly, IL-6, but not IFN-gamma, could significantly impair the in vivo growth of STAT3-depleted human neoplastic T lymphocytes transplanted into severe combined immunodeficient mice. Therefore, treatment with IL-6 and simultaneous STAT3 silencing may represent a potential therapeutic approach to control the expansion of IFN-gamma-unresponsive neoplastic T cells.

An integrated humoral and cellular response is elicited in pancreatic cancer by alpha-enolase, a novel pancreatic ductal adenocarcinoma-associated antigen

Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease with a very poor 5-year survival rate. alpha-Enolase is a glycolytic enzyme that also acts as a surface plasminogen receptor. We find that it is overexpressed in PDAC and present on the cell surface of PDAC cell lines. The clinical correlation of its expression with tumor status has been reported for lung and hepatocellular carcinoma. We have previously demonstrated that sera from PDAC patients contain IgG autoantibodies to alpha-enolase. The present work was intended to assess the ability of alpha-enolase to induce antigen-specific T cell responses. We show that alpha-enolase-pulsed dendritic cells (DC) specifically stimulate healthy autologous T cells to proliferate, secrete IFN-gamma and lyse PDAC cells but not normal cells. In vivo, alpha-enolase-specific T cells inhibited the growth of PDAC cells in immunodeficient mice. In 8 out of 12 PDAC patients with circulating IgG to alpha-enolase, the existence of alpha-enolase-specific T cells was also demonstrated. Taken as a whole, these results indicate that alpha-enolase elicits a PDAC-specific, integrated humoral and cellular response. It is thus a promising and clinically relevant molecular target candidate for immunotherapeutic approaches as new adjuvants to conventional treatments in pancreatic cancer.

CCL16 Enhances the CD8+ and CD4+ T Cell Reactivity to Human Her-2 Elicited by Dendritic Cells Loaded with Rat Ortholog Her-2

T cells from HLA A2+ healthy donors were co-cultured with autologous dendritic cells (DC) loaded with apoptotic tumor cells expressing rat neu, and were induced to mature by tumor necrosis factor (TNF)α and interleukin (IL)-1β (mDC neu) or by the CCL16 chemokine (CCL16/mDC neu). Priming by CCL16/mDC neu induces a larger population of T cells that express cytoplasmatic interferon (IFN)γ, TNFα, perforin and granzyme B compared to those primed by mDC neu. T cells primed by CCL16/mDC neu release IFNγ in response to human HER-2+ cells and kill human HER-2+ target cells more efficiently than those primed by mDC neu. Our results show that both the loading of DC with xenogeneic rat neu and their maturation by CCL16 are two issues of critical importance for the elicitation of an effective response to human HER-2 in T cells from normal donors.

Activin A induces Langerhans cell differentiation in vitro and in human skin explants

Langerhans cells (LC) represent a well characterized subset of dendritic cells located in the epidermis of skin and mucosae. In vivo, they originate from resident and blood-borne precursors in the presence of keratinocyte-derived TGFbeta. In vitro, LC can be generated from monocytes in the presence of GM-CSF, IL-4 and TGFbeta. However, the signals that induce LC during an inflammatory reaction are not fully investigated. Here we report that Activin A, a TGFbeta family member induced by pro-inflammatory cytokines and involved in skin morphogenesis and wound healing, induces the differentiation of human monocytes into LC in the absence of TGFbeta. Activin A-induced LC are Langerin+, Birbeck granules+, E-cadherin+, CLA+ and CCR6+ and possess typical APC functions. In human skin explants, intradermal injection of Activin A increased the number of CD1a+ and Langerin+ cells in both the epidermis and dermis by promoting the differentiation of resident precursor cells. High levels of Activin A were present in the upper epidermal layers and in the dermis of Lichen Planus biopsies in association with a marked infiltration of CD1a+ and Langerin+ cells. This study reports that Activin A induces the differentiation of circulating CD14+ cells into LC. Since Activin A is abundantly produced during inflammatory conditions which are also characterized by increased numbers of LC, we propose that this cytokine represents a new pathway, alternative to TGFbeta, responsible for LC differentiation during inflammatory/autoimmune conditions.

Human dendritic cells differentiated in hypoxia down-modulate antigen uptake and change their chemokine expression profile

Dendritic cells (DCs) are the most potent antigen-presenting cells and fine-tune the immune response. We have investigated hypoxia's effects on the differentiation and maturation of DCs from human monocytes in vitro, and have shown that it affects DC functions. Hypoxic immature DCs (H-iDCs) significantly fail to capture antigens through down-modulation of the RhoA/Ezrin-Radixin-Moesin pathway and the expression of CD206. Moreover, H-iDCs released higher levels of CXCL1, VEGF, CCL20, CXCL8, and CXCL10 but decreased levels of CCL2 and CCL18, which predict a different ability to recruit neutrophils rather than monocytes and create a proinflammatory and proangiogenic environment. By contrast, hypoxia has no effect on DC maturation. Hypoxic mature DCs display a mature phenotype and activate both allogeneic and specific T cells like normoxic mDCs. This study provides the first demonstration that hypoxia inhibits antigen uptake by DCs and profoundly changes the DC chemokine expression profile and may have a critical role in DC differentiation, adaptation, and activation in inflamed tissues.

Transcriptome of hypoxic immature dendritic cells: modulation of chemokine/receptor expression

Hypoxia is a condition of low oxygen tension occurring in inflammatory tissues. Dendritic cells (DC) are professional antigen-presenting cells whose differentiation, migration, and activities are intrinsically linked to the microenvironment. DCs will home and migrate through pathologic tissues before reaching their final destination in the lymph node. We studied the differentiation of human monocytes into immature DCs (iDCs) in a hypoxic microenvironment. We generated iDC in vitro under normoxic (iDCs) or hypoxic (Hi-DCs) conditions and examined the hypoxia-responsive element in the promoter, gene expression, and biochemical KEGG pathways. Hi-DCs had an interesting phenotype represented by up-regulation of genes associated with cell movement/migration. In addition, the Hi-DC cytokine/receptor pathway showed a dichotomy between down-regulated chemokines and up-regulated chemokine receptor mRNA expression. We showed that CCR3, CX3CR1, and CCR2 are hypoxia-inducible genes and that CCL18, CCL23, CCL26, CCL24, and CCL14 are inhibited by hypoxia. A strong chemotactic response to CCR2 and CXCR4 agonists distinguished Hi-DCs from iDCs at a functional level. The hypoxic microenvironment promotes the differentiation of Hi-DCs, which differs from iDCs for gene expression profile and function. The most prominent characteristic of Hi-DCs is the expression of a mobility/migratory rather than inflammatory phenotype. We speculate that Hi-DCs have the tendency to leave the hypoxic tissue and follow the chemokine gradient toward normoxic areas where they can mature and contribute to the inflammatory process.

Lactoferrin, a major defense protein of innate immunity, is a novel maturation factor for human dendritic cells

Lactoferrin (LF) is an important protein component of the innate immune system that is broadly distributed within the body fluids. LF is endowed with multiple biological activities. Talactoferrin (TLF), a recombinant human LF, is in clinical development as an anticancer agent and is entering Phase III clinical trials. Here, we show that TLF induces the maturation of human dendritic cells (DCs) derived from monocytes. TLF, at physiologically relevant concentrations (100 microg/ml) up-regulates the expression of human leukocyte antigen (HLA) class II, CD83, CD80, and CD86 costimulatory molecule and CXCR4 and CCR7 chemokine receptors, acting primarily through the p38 MAPK signaling pathway. DCs matured by TLF displayed an enhanced release of IL-8 and CXCL10, as well as a significantly reduced production of IL-6, IL-10, and CCL20. They also display a reduced ability to take up antigen and increased capacity to trigger proliferation and release IFN-gamma in the presence of allogeneic human T cells. TLF-matured DCs are able to prime naive T cells to respond to KLH antigen and display a significantly increased capacity to present Flu-MA(58-66) peptide to HLA-A2-matched T cells. These data suggest that a key immunomodulatory function that may be mediated by TLF is to link the innate with adaptive immunity through DC maturation.

Autoantibody signature in human ductal pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy characterized by rapid progression, invasiveness, and resistance to treatment. It is the fourth leading cause of cancer death with a 2% 5-year survival rate. Biomarkers for its early detection are lacking. This study was designed to use a proteomics-based approach as a means of identifying antigens that elicit a humoral response in PDAC patients. Antibodies against PDAC-associated antigens are useful for early cancer diagnosis and therapy. Proteins from PDAC cell lines were separated by 2-DE, and the serum IgG reactivity of 70 PDAC patients, 40 healthy subjects (HS), 30 non-PDAC tumor patients, and 15 chronic pancreatitis (CP) patients was tested by Western blot analysis. Spots specifically recognized by PDAC sera and revealed by mass spectrometry corresponded to metabolic enzymes or cytoskeletal proteins. Most were up-regulated in PDAC tissues. Thus, it seems that metabolic enzymes and cytoskeletal proteins are specific targets of the humoral response during PDAC. The results of further studies of these serological-defined antigens could be of diagnostic and therapeutic significance in PDAC.

Alpha-enolase elicits specific pancreatic adenocarcinoma specific-T cell responses in healthy donors and in tumor patients (48.4)

We have demonstrated that sera from pancreatic ductal adenocarcinoma (PDAC) patients contain IgG autoantibodies to α-enolase, a glycolytic enzyme that also works as surface plasminogen receptor. As this implies that α-enolase elicits a B-cell dependent humoral response in vivo in PDAC patients, its ability to induce a T cell mediated response to PDAC was investigated. Here we show that α-enolase-pulsed dendritic cells were capable to specifically stimulate healthy autologous T cells to proliferate, secrete IFN-γ and lyse PDAC cells. In vivo, α-enolase-specific T cells completely inhibited the growth of PDAC cells in immunodeficient mice. In PDAC patients, and in particular in those with circulating IgG autoantibodies to α-enolase, the existence of memory T cells to α-enolase was also demonstrated. As a whole, these results indicate that α-enolase elicits a PDAC-specific humoral and cellular responses. The sum of its features makes α-enolase a promising candidate for new immunotherapeutic strategies in the cure of PDAC that lacks until now of efficacious therapies to associate the conventional ones.

In the absence of IGF-1 signaling, IFN-gamma induces T cell apoptosis (94.14)

IFNg exerts its biological activities by interacting with its cell surface receptor (IFNgR), which consists of two binding chains (R1) and two signal transducing chains (R2).The binding of IFNg to its receptor complex activates the JAK/STAT signal transduction pathway and induces the transcription of IFNg-inducible apoptotic genes. T cells that undergo Th1 polarization or malignant transformation become resistant to the antiproliferative effects of the IFNg/STAT1 pathway.This refractoriness is mainly due to R2 downregulation, due to ligand-independent internalization within clathrin-coated pits. We have previously demonstrated that, by inducing R2 internalization, IGF1 is a critical factors in limiting the IFNg/STAT1 pathway in T cells. Thus, the blockade of its signaling in T cells could hinder their intracellular R2 trafficking and reinstate their sensitivity to IFNg/STAT1 apoptotic signaling. To address this point, a retrovirus-based approach was exploited to stably express a dominant negative form of the IGF1R (IGF1R DN) in ST4 T cell line. Expression of IGF1R DN induced R2 cell surface accumulation and reinstated ST4 cell sensitivity to the IFNg/STAT1 apoptotic pathway in vitro and in vivo. Moreover, the combined exposure to an inhibitor of IGF1R tyrosine kinase activity (picropodophyllin, PPP) and IFNg induced STAT1-dependent apoptosis of three T cell lines (Jurkat ST4 and PF382).These results could be used in the elaboration of new therapeutic approaches based on IGF1 signaling blockade to overcome the resistance of malignant or autoreactive T cells to the apoptotic effect of IFNg.

In the absence of IGF-1 signaling, IFN-gamma suppresses human malignant T-cell growth

Several approaches to target insulin-like growth factor-1 (IGF-1) signaling have resulted in the inhibition of the growth of a broad range of tumor cells. Malignant T cells are insensitive to the antiproliferative effects of the interferon-gamma (IFN-gamma)/signal transducer and activator of transcription 1 (STAT1) pathway because of the IGF-1-dependent internalization of the IFN-gammaR2 signaling chain. Here we show that human malignant T cells are also resistant to the growth inhibitory effect of both the IGF-1 receptor-specific inhibitor picropodophyllin (PPP) and retrovirus-mediated gene transfer of a dominant negative IGF-1 receptor. However, blockade of IGF-1 receptor perturbs IFN-gammaR2 internalization and induces its cell surface accumulation in malignant T cells. This allows the reinstatement of the IFN-gamma-induced STAT1 activation, a high expression of proapoptotic molecules, and the suppression of malignant T-cell growth both in vitro and in vivo in a severe combined immunodeficiency (SCID) mouse model. These data indicate that the inhibition of IGF-1 signaling combined with IFN-gamma administration could be a promising approach to suppress the growth of neoplastic T cells resistant to each treatment on its own.

CC-Chemokine Ligand 16 Induces a Novel Maturation Program in Human Immature Monocyte-Derived Dendritic Cells

Dendritic cells (DCs) are indispensable for initiation of primary T cell responses and a host's defense against infection. Many proinflammatory stimuli induce DCs to mature (mDCs), but little is known about the ability of chemokines to modulate their maturation. In the present study, we report that CCL16 is a potent maturation factor for monocyte-derived DCs (MoDCs) through differential use of its four receptors and an indirect regulator of Th cell differentiation. MoDCs induced to mature by CCL16 are characterized by increased expression of CD80 and CD86, MHC class II molecules, and ex novo expression of CD83 and CCR7. They produce many chemokines to attract monocytes and T cells and are also strong stimulators in activating allogeneic T cells to skew toward Th1 differentiation. Interestingly, they are still able to take up Ag and express chemokine receptors usually bound by inflammatory ligands and can be induced to migrate to different sites where they capture Ags. Our findings indicate that induction of MoDC maturation is an important property of CCL16 and suggest that chemokines may not only organize the migration of MoDCs, but also directly regulate their ability to prime T cell responses.

IL-10 enhances CCL2 release and chemotaxis induced by CCL16 in human monocytes

CCL16 is a CC chemokine originally identified as a liver-expressed chemokine. Its expression has been detected in activated monocytes where it is up-regulated by stimulation with IL-10. This is in contrast with IL-10's inhibition of the expression of most chemokines. CCL16 is chemotactic for monocytes, lymphocyte and dendritic cells. We investigated whether CCL16 displays biological activities other than chemotaxis and whether IL-10 affects monocyte response to CCL16. We show that CCL16 induces the expression of CCL2 at the mRNA and protein level, but does not affect that of CCL5, CCL18 and proinflammatory cytokines. This effect was prevented by treatment with pertussis toxin and may thus be mediated by G-protein-coupled receptors. IL-10 markedly increased CCL2 production induced by CCL16, but suppressed that of CXCL8. It also enhanced the chemotactic response to CCL16. Addition of antibodies blocking CCR1, but not CCR8, prevented this enhanced chemotactic response and suggested that CCR1 is primarily involved. We propose that IL-10 modulates the effects of CCL16 on monocytes by increasing their CCR1-dependent response. The coordinated secretion of CCL16 and IL-10 may thus enhance monocyte infiltration.

Role of dendritic cell-derived CXCL13 in the pathogenesis of Bartonella henselae B-rich granuloma

Dendritic cells (DCs) initiate adaptive immunity and regulate the inflammatory response by producing inflammatory chemokines. This study was aimed to elucidate their role in the pathogenesis of the suppurative granuloma induced by Bartonella henselae infection, which characterizes cat scratch disease (CSD). In vitro DC infection by B. henselae results in internalization of bacteria, phenotypic maturation with increased expression of HLA-DR and CD86, and induction of CD83, CD208, and CCR7. In comparison to LPS-activated DCs, B henselae-infected DCs produce higher amounts of IL-10, whereas the production of IL-12p70 is reduced. Infected DCs also produce high levels of CXCL8 and CXCL13, 2 chemokines active respectively on neutrophils and B lymphocytes. These results provide the molecular basis for the morphogenesis of CSD granuloma, which typically contains high numbers of neutrophils and B cells. Remarkably, CSD granulomas in vivo contain CXCL13-producing DCs. We further demonstrate that the B cells in CSD granulomas are represented by monocytoid B cells and, worth noting, they express T-bet, a transcription factor able to induce a T-independent immunoglobulin (Ig) class switch in B lymphocytes. These findings suggest that the humoral immune response to B henselae initiates in the extrafollicular areas of infected lymph nodes and is regulated by DCs.

Iron regulates T-lymphocyte sensitivity to the IFN-gamma/STAT1 signaling pathway in vitro and in vivo

The refractoriness of T cells to the interferon-gamma (IFN-gamma)/signal transducer and activator of transcription 1 (STAT1) pathway, which shields them from the antiproliferative effect of IFN-gamma, is attributed mainly to down-regulation of the IFN-gammaR2 signaling chain. However, the mechanisms responsible for this down-regulation are unclear. Here we show that iron uptake mediated by the transferrin receptor (TfR) delivers a signal that leads to IFN-gammaR2 internalization and thus plays an essential role in attenuating activation of the IFN-gamma/STAT1 pathway in human T lymphocytes. The effect of iron on IFN-gammaR2 internalization was specific as it did not affect expression of the IFN-gammaR1 binding chain. Deferoxamine (DFO), an iron-chelating agent, up-regulated IFN-gammaR2 surface expression and reinstated IFN-gamma/STAT1 activation in proliferating T lymphocytes. Resistance of malignant T cells to the antiproliferative effect of IFN-gamma in vitro was abrogated by addition of DFO. Conversely, iron inhibited IFN-gamma-induced apoptosis in malignant T cells in serum-free conditions. In combination but not individually, DFO and IFN-gamma strongly inhibited growth of human malignant T cells in an in vivo severe combined immunodeficient (SCID) mouse model. These data provide valuable insights for novel therapeutic approaches aimed at reinstating the IFN-gamma/STAT1 apoptotic signaling pathway in autoreactive or neoplastic T cells by means of iron chelation.

Immunological mechanisms elicited at the tumour site by lymphocyte activation gene-3 (LAG-3) versus IL-12: sharing a common Th1 anti-tumour immune pathway

The experimentally induced TS/A murine mammary carcinoma is poorly immunogenic and mainly infiltrated by antigen-presenting cells (APCs), namely macrophages and immature dendritic cells (DCs). Human (h) and mouse (m) lymphocyte activation gene-3 (LAG-3 or CD233) is a physiological MHC class II ligand and powerful APC activator. A gene transfer approach has revealed its anti-tumour activity in this model: hLAG-3 was more effective than mLAG-3. To obtain a clearer picture of the immunoregulatory mechanisms associated with the rejection dynamics of h- and m-LAG-3 transfectants, immunohistochemistry and confocal microscopy analyses of TS/A-hLAG-3, TS/A-mLAG-3, and control TS/A-pc tumours were performed. The immune events elicited by mLAG-3 and m-interleukin (IL)-12 were also compared, since their rejection kinetics were quite similar, and LAG-3 enables IL-12 production by macrophages and DCs. Both the TS/A-h- and, to a lesser extent, the m-LAG-3 rejection areas were characterized by an impressive recruitment of APCs, granulocytes, NK cells, CD4+ T lymphocytes and CD8+ IFNgamma-expressing cells. In both cases, infiltration by APCs was accompanied by strong CD80 and CD86 expression and macrophage nitric oxide (NO) synthase up-regulation. Distinct expression of IL-12 and CXCL9 was also found, especially in the draining lymph nodes. T lymphocytes and CD86-expressing APCs were significantly prevalent in both the TS/A-h- and the m-LAG-3 compared with the TS/A-mIL-12 rejection area. Production of IFNgamma, TNFalpha and IL1beta, and chemokines, namely CXCL5, CXCL9, CXCL10, CXCL11, CCL5, and CCL2, by infiltrating leukocytes and signs of defective neovascularization were detected in tumours expressing h-LAG-3-, m-LAG-3-, and m-IL-12. However, IFNgamma, CCL2, and CCL5 production prevailed in the TS/A-hLAG-3 rejection area. Taken together, these results indicate that LAG-3 expression by engineered tumour cells efficiently promotes intra-tumoural recruitment, activation, and Th1 commitment of APCs, and leads to a wide intra-tumoural influx of non-specific and specific reactive cells, and the release of immunoregulatory and cytotoxic mediators. Many of LAG-3's anti-tumour activities are shared with IL-12.

Intralesional Injection of Adenovirus Encoding CC Chemokine Ligand 16 Inhibits Mammary Tumor Growth and Prevents Metastatic-Induced Death after Surgical Removal of the Treated Primary Tumor

The CC chemokine ligand (CCL)16 exerts chemotactic activity on human monocytes and lymphocytes. Although no murine homologous has been defined, the TSA mouse adenocarcinoma cells engineered to express human CCL16 are rapidly rejected by syngenic mice. An adenovirus encoding CCL16 (AdCCL16) was generated using a Cre-Lox-based system and was used to determine whether this chemokine might also block pre-existing tumors. Both recombinant and viral CCL16 showed in vitro chemotactic activity for murine CD4(+) and CD8(+) lymphocytes and dendritic cells (DC). AdCCL16, but not the control empty vector, when injected in established nodules significantly delayed tumor growth. Immunohistochemistry revealed accumulation of CD4(+) and CD8(+) T cells and DC in the treated tumors as well as in draining lymph nodes. DC from such lymph nodes stimulated IFN-gamma by a T cell clone specific for the known TSA tumor-associated Ag (TAA), suggesting the tumor origin of these cells. Lymphocytes from the same nodes showed specific CTL activity against TSA tumor cells and their immunodominant TAA peptide. Antitumor activity required CD4, CD8, and IFN-gamma production, as shown using subset-depleted and knockout mice. Despite the robust and rapid immune response triggered by intratumoral injection of AdCCL16, the lesions were not completely rejected; however, the same treatment given before surgical excision of primary lesions prevented metastatic spread and cured 63% of mice bearing the 4T1 mammary adenocarcinoma, which is perhaps the most compelling model of spontaneous metastasis.

The interferon-inducible IFI16 gene inhibits tube morphogenesis and proliferation of primary, but not HPV16 E6/E7-immortalized human endothelial cells

Immunohistochemical analysis has demonstrated that the human IFI16 gene, in addition to the hematopoietic tissues, is highly expressed in endothelial cells and squamous stratified epithelia. In this study, we have developed a reliable HSV-derived replication-defective vector (TO-IFI16) to efficiently transduce IFI16 into primary human umbilical vein endothelial cells (HUVEC), which are usually poorly transfectable. HUVEC infection with TO-IFI16 virus suppressed endothelial migration, invasion and formation of capillary-like structures in vitro. In parallel, sustained IFI16 expression inhibited HUVEC cell cycle progression, accompanied by significant induction of p53, p21, and hypophosphorylated pRb. Further support for the involvement of these pathways in IFI16 activity came from the finding that infection with TO-IFI16 virus does not impair the in vitro angiogenic activity and cell cycle progression of HUVEC immortalized by HPV16 E6/E7 oncogenes, which are known to inactivate both p53 and pRb systems. This use of a reliable viral system for gene delivery into primary human endothelial cells assigns a potent angiostatic activity to an IFN-inducible gene, namely IFI16, and thus throws further light on antiangiogenic therapy employing IFNs.

CCL16 activates an angiogenic program in vascular endothelial cells

Besides regulating leukocyte trafficking in normal and injured tissues, several chemokines may positively or negatively regulate angiogenesis. Here we report that CCL16 activates an angiogenic program in vascular endothelial cells by activating CCR1. CCL16 induces dose-dependent random and directional migration of endothelial cells isolated from large vessels and liver capillaries without inducing their proliferation. It also promotes endothelial differentiation into capillary-like structures in an in vitro assay and is angiogenic in the chick chorionallantoic membrane. These angiogenic activities are neutralized by a specific antibody against CCL16. The direct angiogenic activity of CCL16 is further amplified by its ability to prime endothelium to a mitogen signal induced by vascular endothelial growth factor A and to raise their basal production of CXCL8 and CCL2, 2 other angiogenic chemokines. BX471 (R-N-[5-chloro-2-[2-[4(4-fluorophenyl) methyl]-2-methyl-1-piperazinyl]-2-oxoethoxy]phenyl] urea hydrochloric acid salt), a CCR1 antagonist, inhibits angiogenic properties of CCL16, whereas blocking of CCR8 or desensitizing CCR2, which are both well known receptors for CCL16, did not abolish endothelial activation. CCL16 may be specifically cross-linked to CCR1 expressed on endothelial cells. The largely restricted CCL16 expression in the liver suggests that this chemokine may play a role in hepatic vascular formation during development and in angiogenesis associated to hepatic diseases.