An engineered Accum-E7 protein-based vaccine with dual anti-cervical cancer activity

Worldwide prevalence of cervical cancer decreased significantly with the use of human papilloma virus (HPV)-targeted prophylactic vaccines. However, these multivalent antiviral vaccines are inert against established tumors, which leave patients with surgical ablative options possibly resulting in long-term reproductive complications and morbidity. In an attempt to bypass this unmet medical need, we designed a new E7 protein-based vaccine formulation using Accum™, a technology platform designed to promote endosome-to-cytosol escape as a means to enhance protein accumulation in target cells. Prophylactic vaccination of immunocompetent mice using the Accum-E7 vaccine (aE7) leads to complete protection from cervical cancer despite multiple challenges conducted with ascending C3.43 cellular doses (0.5-, 1.0-, and 2.0 × 106 cells). Moreover, the humoral response induced by aE7 was higher in magnitude compared with naked E7 protein vaccination and displayed potent inhibitory effects on C3.43 proliferation in vitro. When administered therapeutically to animals with pre-established C3.43 or Tal3 tumors, the vaccine-induced response synergized with multiple immune checkpoint blockers (anti-PD-1, anti-CTLA4, and anti-CD47) to effectively control tumor growth. Mechanistically, the observed therapeutic effect requires cross-presenting dendritic cells as well as CD8 T cells predominantly, with a non-negligible role played by both CD4+ and CD19+ lymphocytes. good laboratory practice (GLP) studies revealed that aE7 is immunogenic and well tolerated by immunocompetent mice with no observed adverse effects despite the use of a fourfold exceeding dose. In a nutshell, aE7 represents an ideal vaccine candidate for further clinical development as it uses a single engineered protein capable of exhibiting both prophylactic and therapeutic activity.

A1-reprogrammed mesenchymal stromal cells prime potent antitumoral responses

Mesenchymal stromal cells (MSCs) have been modified via genetic or pharmacological engineering into potent antigen-presenting cells-like capable of priming responding CD8 T cells. In this study, our screening of a variant library of Accum molecule revealed a molecule (A1) capable of eliciting antigen cross-presentation properties in MSCs. A1-reprogrammed MSCs (ARM) exhibited improved soluble antigen uptake and processing. Our comprehensive analysis, encompassing cross-presentation assays and molecular profiling, among other cellular investigations, elucidated A1's impact on endosomal escape, reactive oxygen species production, and cytokine secretion. By evaluating ARM-based cellular vaccine in mouse models of lymphoma and melanoma, we observe significant therapeutic potency, particularly in allogeneic setting and in combination with anti-PD-1 immune checkpoint inhibitor. Overall, this study introduces a strong target for developing an antigen-adaptable vaccination platform, capable of synergizing with immune checkpoint blockers to trigger tumor regression, supporting further investigation of ARMs as an effective and versatile anti-cancer vaccine.

Intratumoral administration of unconjugated Accum™ impairs the growth of pre-established solid lymphoma tumors

The Accum™ technology was initially designed to enhance the bioaccumulation of a given molecule in target cells. It does so by triggering endosomal membrane damages allowing endocytosed products to enter the cytosol, escaping the harsh environmental cues of the endosomal lumen. In an attempt to minimize manufacturing hurdles associated with Accum™ conjugation, we tested whether free Accum™ admixed with antigens could lead to outcomes similar to those obtained with conjugated products. Surprisingly, unconjugated Accum™ was found to promote cell death in vitro, an observation further confirmed on various murine tumor cell lines (EL4, CT-26, B16, and 4 T1). At the molecular level, unconjugated Accum™ triggers the production of reactive oxygen species and elicits immunogenic cell death while retaining its innate ability to cause endosomal damages. When administered as a monotherapy to animals with pre-established EL4 T-cell lymphoma, Accum™ controlled tumor growth in a dose-dependent manner, and its therapeutic effect relies on CD4 and CD8 T cells. Although unconjugated Accum™ synergizes with various immune checkpoint inhibitors (anti-CTLA4, anti-PD-1, or anti-CD47) at controlling tumor growth, its therapeutic potency could not be further enhanced when combined with all three tested immune checkpoint inhibitors at once due to its dependency on a specific dosing regimen. In sum, we report in this study an unprecedented new function for unconjugated Accum™ as a novel anticancer molecule. These results could pave the path for a new line of investigation aimed at exploring the pro-killing properties of additional Accum™ variants as a mean to develop second-generation anticancer therapeutics.

CD146 Defines a Mesenchymal Stromal Cell Subpopulation with Enhanced Suppressive Properties

Mesenchymal stromal cells (MSCs) are largely known for their immune-suppressive capacity, hence, their common use in the control of unwanted inflammation. However, novel concepts related to their biology, combined with the urgent need to identify MSC subpopulations with enhanced suppressive properties, drive the search for isolation protocols optimized for clinical applications. We show, in this study, that MSCs expressing high CD146 levels exhibit altered surface expression profiles of CD44 and secrete elevated levels of interleukin (IL)-6, amongst other factors. In addition, CD146^hi MSCs surpass the polyclonal parental populations in inhibiting alloreactive T cells in vitro, in both a soluble- and cell-contact-dependent manner. Despite the lack of CD146^hi MSC-mediated activation of peritoneal macrophages to release the suppressive factor IL-10 in vitro, their administration in animals with graft-versus-host disease alleviates inflammation and leads to 40% survival rate up to 7 weeks post-transplantation. This pronounced inhibitory property is driven by CD146-mediated in situ efferocytosis by myeloid cells. Altogether, this study provides the impetus to adopt an isolation protocol for MSCs based on a CD146 expression profile before their therapeutic use and suggests a major role played by CD146 as a novel “eat-me” signal, capable of enhancing MSC uptake by competent phagocytes.

Promoting antigen escape from dendritic cell endosomes potentiates anti-tumoral immunity

The cross-presenting capacity of dendritic cells (DCs) can be limited by non-specific degradation during endosome maturation. To bypass this limitation, we present in this study a new Accum-based formulation designed to promote endosome-to-cytosol escape. Treatment of primary DCs with Accum linked to the xenoantigen ovalbumin (OVA) triggers endosomal damages and enhances protein processing. Despite multiple challenges using ascending doses of tumor cells, DC prophylactic vaccination results in complete protection due to increased levels of effector CD4 and CD8 T cells as well as high production of pro-inflammatory mediators. When combined with anti-PD-1, therapeutic vaccination using both syngeneic and allogeneic Accum-OVA-pulsed DCs triggers potent anti-tumoral responses. The net outcome culminates in increased CD11c, CD8, and NK infiltration along with a high CD8/Treg ratio. These highly favorable therapeutic effects highlight the promising potential of Accum as a distinct and potent technology platform suitable for the design of next generation cell cancer vaccines.

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Accum-linked antigen enhances antigen processing and presentation

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Pulsed dendritic cells elicit potent effector T cell responses

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Therapeutic vaccination using allogeneic DCs controls pre-established tumors

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The vaccine boosts tumor-infiltrating lymphocytes and increases the CD8/Treg ratio

Humoral Immunity to Allogeneic Immunoproteasome-Expressing Mesenchymal Stromal Cells Requires Efferocytosis by Endogenous Phagocytes

The extensive use of mesenchymal stromal cells (MSCs) over the last decade has revolutionized modern medicine. From the delivery of pharmacological proteins to regenerative medicine and immune modulation, these cells have proven to be highly pleiotropic and responsive to their surrounding environment. Nevertheless, their role in promoting inflammation has been fairly limited by the questionable use of interferon-gamma, as this approach has also been proven to enhance the cells' immune-suppressive abilities. Alternatively, we have previously shown that de novo expression of the immunoproteasome (IPr) complex instills potent antigen cross-presentation capabilities in MSCs. Interestingly, these cells were found to express the major histocompatibility class (MHC) II protein, which prompted us to investigate their ability to stimulate humoral immunity. Using a series of in vivo studies, we found that administration of allogeneic ovalbumin (OVA)-pulsed MSC-IPr cells elicits a moderate antibody titer, which was further enhanced by the combined use of pro-inflammatory cytokines. The generated antibodies were functional as they blocked CD4 T-cell activation following their co-culture with OVA-pulsed MSC-IPr and mitigated E.G7 tumor growth in vivo. The therapeutic potency of MSC-IPr was, however, dependent on efferocytosis, as phagocyte depletion prior to vaccination abrogated MSC-IPr-induced humoral responses while promoting their survival in the host. In contrast, antibody-mediated neutralization of CD47, a potent "do not eat me signal", enhanced antibody titer levels. These observations highlight the major role played by myeloid cells in supporting antibody production by MSC-IPr and suggest that the immune outcome is dictated by a net balance between efferocytosis-stimulating and -inhibiting signals.

Engineering immunoproteasome-expressing mesenchymal stromal cells: A potent cellular vaccine for lymphoma and melanoma in mice

Dendritic cells (DCs) excel at cross-presenting antigens, but their effectiveness as cancer vaccine is limited. Here, we describe a vaccination approach using mesenchymal stromal cells (MSCs) engineered to express the immunoproteasome complex (MSC-IPr). Such modification instills efficient antigen cross-presentation abilities associated with enhanced major histocompatibility complex class I and CD80 expression, de novo production of interleukin-12, and higher chemokine secretion. This cross-presentation capacity of MSC-IPr is highly dependent on their metabolic activity. Compared with DCs, MSC-IPr hold the ability to cross-present a vastly different epitope repertoire, which translates into potent re-activation of T cell immunity against EL4 and A20 lymphomas and B16 melanoma tumors. Moreover, therapeutic vaccination of mice with pre-established tumors efficiently controls cancer growth, an effect further enhanced when combined with antibodies targeting PD-1, CTLA4, LAG3, or 4-1BB under both autologous and allogeneic settings. Therefore, MSC-IPr constitute a promising subset of non-hematopoietic antigen-presenting cells suitable for designing universal cell-based cancer vaccines.

Thymoproteasome-Expressing Mesenchymal Stromal Cells Confer Protective Anti-Tumor Immunity via Cross-Priming of Endogenous Dendritic Cells

Proteasomes are complex macromolecular structures existing in various forms to regulate a myriad of cellular processes. Besides degrading unwanted or misfolded proteins (proteostasis), distinct immune functions were ascribed for the immunoproteasome and thymoproteasome (TPr) complexes. For instance, antigen degradation during ongoing immune responses mainly relies on immunoproteasome activity, whereas intrathymic CD8 T-cell development requires peptide generation by the TPr complex. Despite these substantial differences, the functional contribution of the TPr to peripheral T-cell immunity remains ill-defined. We herein explored whether the use of mesenchymal stromal cells (MSCs) engineered to exhibit altered proteasomal activity through de novo expression of the TPr complex can be exploited as a novel anti-cancer vaccine capable of triggering potent CD8 T-cell activation. Phenotypic and molecular characterization of MSC-TPr revealed a substantial decrease in MHCI (H2-K^b and H2-D^d) expression along with elevated secretion of various chemokines (CCL2, CCL9, CXCL1, LIX, and CX3CL1). In parallel, transcriptomic analysis pinpointed the limited ability of MSC-TPr to present endogenous antigens, which is consistent with their low expression levels of the peptide-loading proteins TAP, CALR, and PDAI3. Nevertheless, MSC-TPr cross-presented peptides derived from captured soluble proteins. When tested for their protective capacity, MSC-TPr triggered modest anti-tumoral responses despite efficient generation of effector memory CD4 and CD8 T cells. In contrast, clodronate administration prior to vaccination dramatically enhanced the MSC-TPr-induced anti-tumoral immunity clearly highlighting a refractory role mediated by phagocytic cells. Thus, our data elute to a DC cross-priming-dependant pathway in mediating the therapeutic effect of MSC-TPr.

TACIMA-218: A Novel Pro-Oxidant Agent Exhibiting Selective Antitumoral Activity

We report the discovery, via a unique high-throughput screening strategy, of a novel bioactive anticancer compound: Thiol Alkylating Compound Inducing Massive Apoptosis (TACIMA)-218. We demonstrate that this molecule engenders apoptotic cell death in genetically diverse murine and human cancer cell lines, irrespective of their p53 status, while sparing normal cells. TACIMA-218 causes oxidative stress in the absence of protective antioxidants normally induced by Nuclear factor erythroid 2-related factor 2 activation. As such, TACIMA-218 represses RNA translation and triggers cell signaling cascade alterations in AKT, p38, and JNK pathways. In addition, TACIMA-218 manifests thiol-alkylating properties resulting in the disruption of redox homeostasis along with key metabolic pathways. When administered to immunocompetent animals as a monotherapy, TACIMA-218 has no apparent toxicity and induces complete regression of pre-established lymphoma and melanoma tumors. In sum, TACIMA-218 is a potent oxidative stress inducer capable of selective cancer cell targeting.

A Novel Sulfonyl-Based Small Molecule Exhibiting Anti-cancer Properties

Phenotypic screening is an ideal strategy for the discovery of novel bioactive molecules. Using a customized high-throughput screening (HTS) assay employing primary T lymphocytes, we screened a small library of 4,398 compounds with unknown biological function/target to identify compounds eliciting immunomodulatory properties and discovered a sulfonyl-containing hit, we named InhiTinib. This compound inhibited interferon (IFN)-gamma production and proliferation of primary CD3⁺ T cells without inducing cell death. In contrast, InhiTinib triggered apoptosis in several murine and human cancer cell lines. Besides, the compound was well tolerated by immunocompetent mice, triggered tumor regression in animals with pre-established EL4 T-cell lymphomas, and prolonged the overall survival of mice harboring advanced tumors. Altogether, our data demonstrate the anti-cancer properties of InhiTinib, which can henceforth bridge to wider-scale biochemical and clinical tests following further in-depth pharmacodynamic studies.

Mesenchymal Stem Cells Beyond Regenerative Medicine

Mesenchymal stem cells (MSCs) are competent suitors of cellular therapy due to their therapeutic impact on tissue degeneration and immune-based pathologies. Additionally, their homing and immunomodulatory properties can be exploited in cancer malignancies to transport pharmacological entities, produce anti-neoplastic agents, or induce anti-tumor immunity. Herein, we create a portfolio for MSC properties, showcasing their distinct multiple therapeutic utilities and successes/challenges thereof in both animal studies and clinical trials. We further highlight the promising potential of MSCs not only in cancer management but also in instigating tumor-specific immunity - i.e., cancer vaccination. Finally, we reflect on the possible reasons impeding the clinical advancement of MSC-based cancer vaccines to assist in contriving novel methodologies from which a therapeutic milestone might emanate.

An overview of the role of lipid peroxidation-derived 4-hydroxynonenal in osteoarthritis

BACKGROUND

Over the years, many theories have been proposed and examined to better explain the etiology and development of osteoarthritis (OA). The characteristics of joint destruction are one of the most important aspects in disease progression. Therefore, investigating different factors and signaling pathways involved in the alteration of extracellular matrix (ECM) turnover, and the subsequent catabolic damage to cartilage holds chief importance in understanding OA development. Among these factors, reactive oxygen species (ROS) have been at the forefront of the physiological and pathophysiological OA investigation.

FINDINGS

In the last decades, research studies provided an enormous volume of data supporting the involvement of ROS in OA. Most interestingly, published data regarding the effect of exogenous antioxidant therapy in OA lack conclusive results from clinical trials to back up in vitro data. Accordingly, it is rational to suggest that there are other reactive species in OA that are not taken into account. Thus, our present review is focused on our current understanding of the involvement of lipid peroxidation-derived 4-hydroxynonenal (HNE) in OA.

CONCLUSION

Our findings, like those in the literature, illustrate the central role played by HNE in the regulation of a number of factors involved in joint homeostasis. HNE could thus be considered as an attractive therapeutic target in OA.

Elucidating the Role of Protandim and 6-Gingerol in Protection Against Osteoarthritis

Protandim and 6-gingerol, two potent nutraceuticals, have been shown to decrease free radicals production through enhancing endogenous antioxidant enzymes. In this study, we evaluated the effects of these products on the expression of different factors involved in osteoarthritis (OA) process. Human OA chondrocytes were treated with 1 ng/ml IL-1β in the presence or absence of protandim (0-10 μg/ml) or 6-gingerol (0-10 μM). OA was induced surgically in mice by destabilization of the medial meniscus (DMM). The animals were treated weekly with an intraarticular injection of 10 μl of vehicle or protandim (10 μg/ml) for 8 weeks. Sham-operated mice served as controls. In vitro, we demonstrated that protandim and 6-gingerol preserve cell viability and mitochondrial metabolism and prevented 4-hydroxynonenal (HNE)-induced cell mortality. They activated Nrf2 transcription factor, abolished IL-1β-induced NO, PGE₂ , MMP-13, and HNE production as well as IL-β-induced GSTA4-4 down-regulation. Nrf2 overexpression reduced IL-1β-induced HNE and MMP-13 as well as IL-1β-induced GSTA4-4 down-regulation. Nrf2 knockdown following siRNA transfection abolished protandim protection against oxidative stress and catabolism. The activation of MAPK and NF-κB by IL-1β was not affected by 6-gingerol. In vivo, we observed that Nrf2 and GSTA4-4 expression was significantly lower in OA cartilage from humans and mice compared to normal controls. Interestingly, protandim administration reduced OA score in DMM mice. Altogether, our data indicate that protandim and 6-gingerol are essential in preserving cartilage and abolishing a number of factors known to be involved in OA pathogenesis. J. Cell. Biochem. 118: 1003-1013, 2017. © 2016 Wiley Periodicals, Inc.

Ramipril attenuates lipid peroxidation and cardiac fibrosis in an experimental model of rheumatoid arthritis

INTRODUCTION

Recent studies revealed that co-morbidity and mortality due to cardiovascular disease are increased in patients with rheumatoid arthritis (RA) but little is known about factors involved in these manifestations. This study aimed at characterizing the impact of arthritis on oxidative stress status and tissue fibrosis in the heart of rats with adjuvant-induced arthritis (AIA).

METHODS

AIA was induced with complete Freund's adjuvant in female Lewis rats. Animals were treated by oral administration of vehicle or angiotensin-converting enzyme inhibitor ramipril (10 mg/kg/day) for 28 days, beginning 1 day after arthritis induction. Isolated adult cardiomyocytes were exposed to 10 μM 4-hydroxynonenal (HNE) for 24 hours in the presence or absence of 10 μM ramipril.

RESULTS

Compared to controls, AIA rats showed significant 55 and 30% increase of 4-HNE/protein adducts in serum and left ventricular (LV) tissues, respectively. Cardiac mitochondrial NADP+-isocitrate dehydrogenase (mNADP-ICDH) activity decreased by 25% in AIA rats without any changes in its protein and mRNA expression. The loss of mNADP-ICDH activity was correlated with enhanced accumulation of HNE/mNADP-ICDH adducts as well as with decrease of glutathione and NADPH. Angiotensin II type 1 receptor (AT1R) expression and tissue fibrosis were induced in LV tissues from AIA rats. In isolated cardiomyocytes, HNE significantly decreased mNADP-ICDH activity and enhanced type I collagen and connective tissue growth factor expression. The oral administration of ramipril significantly reduced HNE and AT1R levels and restored mNADP-ICDH activity and redox status in LV tissues of AIA rats. The protective effects of this drug were also evident from the decrease in arthritis scoring and inflammatory markers.

CONCLUSION

Collectively, our findings disclosed that AIA induced oxidative stress and fibrosis in the heart. The fact that ramipril attenuates inflammation, oxidative stress and tissue fibrosis may provide a novel strategy to prevent heart diseases in RA.