Cell-type-specific innate immune response to oncolytic Newcastle disease virus

Personalizing Oncolytic Immunovirotherapy Approaches

Development of successful cancer therapeutics requires exploration of the differences in genetics, metabolism, and interactions with the immune system among malignant and normal cells. The clinical observation of spontaneous tumor regression following natural infection with microorganism has created the premise of their use as cancer therapeutics. Oncolytic viruses (OVs) originate from viruses with attenuated virulence in humans, well-characterized vaccine strains of known human pathogens, or engineered replication-deficient viral vectors. Their selectivity is based on receptor expression level and post entry restriction factors that favor replication in the tumor, while keeping the normal cells unharmed. Clinical trials have demonstrated a wide range of patient responses to virotherapy, with subgroups of patients significantly benefiting from OV administration. Tumor-specific gene signatures, including antiviral interferon-stimulated gene (ISG) expression profile, have demonstrated a strong correlation with tumor permissiveness to infection. Furthermore, the combination of OVs with immunotherapeutics, including anticancer vaccines and immune checkpoint inhibitors [ICIs, such as anti-PD-1/PD-L1 or anti-CTLA-4 and chimeric antigen receptor (CAR)-T or CAR-NK cells], could synergistically improve the therapeutic outcome. Creating response prediction algorithms represents an important step for the transition to individualized immunovirotherapy approaches in the clinic. Integrative predictors could include tumor mutational burden (TMB), inflammatory gene signature, phenotype of tumor-infiltrating lymphocytes, tumor microenvironment (TME), and immune checkpoint receptor expression on both immune and target cells. Additionally, the gut microbiota has recently been recognized as a systemic immunomodulatory factor and could further be used in the optimization of individualized immunovirotherapy algorithms.

The NP protein of Newcastle disease virus dictates its oncolytic activity by regulating viral mRNA translation efficiency

Newcastle disease virus (NDV) has been extensively studied as a promising oncolytic virus for killing tumor cells in vitro and in vivo in clinical trials. However, the viral components that regulate the oncolytic activity of NDV remain incompletely understood. In this study, we systematically compared the replication ability of different NDV genotypes in various tumor cells and identified NP protein determines the oncolytic activity of NDV. On the one hand, NDV strains with phenylalanine (F) at the 450th amino acid position of the NP protein (450th-F-NP) exhibit a loss of oncolytic activity. This phenotype is predominantly associated with genotype VII NDVs. In contrast, the NP protein with a leucine amino acid at this site in other genotypes (450th-L-NP) can facilitate the loading of viral mRNA onto ribosomes more effectively than 450th-F-NP. On the other hand, the NP protein from NDV strains that exhibit strong oncogenicity interacts with eIF4A1 within its 366-489 amino acid region, leading to the inhibition of cellular mRNA translation with a complex 5' UTR structure. Our study provide mechanistic insights into how highly oncolytic NDV strains selectively promote the translation of viral mRNA and will also facilitate the screening of oncolytic strains for oncolytic therapy.

Transcriptome Analysis of Natural Killer Cells in Response to Newcastle Disease Virus Infected Hepatocellular Carcinoma Cells

When tumor cells are infected by the Newcastle disease virus (NDV), the lysis of tumor cells by natural killer (NK) cells is enhanced, which may be related to the enhanced NK cell activation effect. To better understand the intracellular molecular mechanisms involved in NK cell activation, the transcriptome profiles of NK cells stimulated by NDV-infected hepatocellular carcinoma (HCC) cells (NDV group) and control (NC group, NK cells stimulated by HCC cells) were analyzed. In total, we identified 1568 differentially expressed genes (DEGs) in the NK cells of the NDV group compared to the control, including 1389 upregulated and 179 downregulated genes. Functional analysis showed that DEGs were enriched in the immune system, signal transmission, cell growth, cell death, and cancer pathways. Notably, 9 genes from the IFN family were specifically increased in NK cells upon NDV infection and identified as potential prognosis markers for patients with HCC. A qRT-PCR experiment was used to confirm the differential expression of IFNG and the other 8 important genes. The results of this study will improve our understanding of the molecular mechanisms of NK cell activation.

Robust delivery of RIG-I agonists using extracellular vesicles for anti-cancer immunotherapy

The RIG-I pathway can be activated by RNA containing 5' triphosphate, leading to type I interferon release and immune activation. Hence, RIG-I agonists have been used to induce immune responses against cancer as potential immunotherapy. However, delivery of 5' triphosphorylated RNA molecules as RIG-I agonists to tumour cells in vivo is challenging due to the susceptibility of these molecules to degradation. In this study, we demonstrate the use of extracellular vesicles (EVs) from red blood cells (RBCs), which are highly amenable for RNA loading and taken up robustly by cancer cells, for RIG-I agonist delivery. We evaluate the anti-cancer activity of two novel RIG-I agonists, the immunomodulatory RNA (immRNA) with a unique secondary structure for efficient RIG-I activation, and a 5' triphosphorylated antisense oligonucleotide with dual function of RIG-I activation and miR-125b inhibition (3p-125b-ASO). We find that RBCEV-delivered immRNA and 3p-125b-ASO trigger the RIG-I pathway, and induce cell death in both mouse and human breast cancer cells. Furthermore, we observe a significant suppression of tumour growth coupled with increased immune cell infiltration mediated by the activation of RIG-I cascade after multiple intratumoral injections of RBCEVs loaded with immRNA or 3p-125b-ASO. Targeted delivery of immRNA using RBCEVs with EGFR-binding nanobody administrated via intrapulmonary delivery facilitates the accumulation of RBCEVs in metastatic cancer cells, leading to potent tumour-specific CD8+ T cells immune response. This contributes to prominent suppression of breast cancer metastasis in the lung. Hence, this study provides a new strategy for efficient RIG-I agonist delivery using RBCEVs for immunotherapy against cancer and cancer metastasis.

Persistent Newcastle disease virus infection in bladder cancer cells is associated with putative pro-survival and anti-viral transcriptomic changes

Background

Newcastle disease virus (NDV) is an oncolytic virus with excellent selectivity against cancer cells, both in vitro and in vivo. Unfortunately, prolonged in vitro NDV infection results in the development of persistent infection in the cancer cells which are then able to resist NDV-mediated oncolysis. However, the mechanism of persistency of infection remains poorly understood.

Methods

In this study, we established persistently NDV-infected EJ28 bladder cancer cells, designated as EJ28P. Global transcriptomic analysis was subsequently carried out by microarray analysis. Differentially expressed genes (DEGs) between EJ28 and EJ28P cells identified by the edgeR program were further analysed by Gene Set Enrichment Analysis (GSEA) and Ingenuity Pathway Analysis (IPA) analyses. In addition, the microarray data were validated by RT-qPCR.

Results

Persistently NDV-infected EJ28 bladder cancer cells were successfully established and confirmed by flow cytometry. Microarray analysis identified a total of 368 genes as differentially expressed in EJ28P cells when compared to the non-infected EJ28 cells. GSEA revealed that the Wnt/β-catenin and KRAS signalling pathways were upregulated while the TGF-β signalling pathway was downregulated. Findings from this study suggest that the upregulation of genes that are associated with cell growth, pro-survival, and anti-apoptosis may explain the survivability of EJ28P cells and the development of persistent infection of NDV.

Conclusions

This study provides insights into the transcriptomic changes that occur and the specific signalling pathways that are potentially involved in the development and maintenance of NDV persistency of infection in bladder cancer cells. These findings warrant further investigation and is crucial towards the development of effective NDV oncolytic therapy against cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08345-y.

Newcastle Disease Virus at the Forefront of Cancer Immunotherapy

Preclinical and clinical studies dating back to the 1950s have demonstrated that Newcastle disease virus (NDV) has oncolytic properties and can potently stimulate antitumor immune responses. NDV selectively infects, replicates within, and lyses cancer cells by exploiting defective antiviral defenses in cancer cells. Inflammation within the tumor microenvironment in response to NDV leads to the recruitment of innate and adaptive immune effector cells, presentation of tumor antigens, and induction of immune checkpoints. In animal models, intratumoral injection of NDV results in T cell infiltration of both local and distant non-injected tumors, demonstrating the potential of NDV to activate systemic adaptive antitumor immunity. The combination of intratumoral NDV with systemic immune checkpoint blockade leads to regression of both injected and distant tumors, an effect further potentiated by introduction of immunomodulatory transgenes into the viral genome. Clinical trials with naturally occurring NDV administered intravenously demonstrated durable responses across numerous cancer types. Based on these studies, further exploration of NDV is warranted, and clinical studies using recombinant NDV in combination with immune checkpoint blockade have been initiated.

Avian Pattern Recognition Receptor Sensing and Signaling

Pattern recognition receptors (PRRs) are a class of immune sensors that play a critical role in detecting and responding to several conserved patterns of microorganisms. As such, they play a major role in the maintenance of immune homeostasis and anti-microbial defense. Fundamental knowledge pertaining to the discovery of PRR functions and their ligands continue to advance the understanding of immune system and disease resistance, which led to the rational design and/or application of various PRR ligands as vaccine adjuvants. In addition, the conserved nature of many PRRs throughout the animal kingdom has enabled the utilization of the comparative genomics approach in PRR identification and the study of evolution, structural features, and functions in many animal species including avian. In the present review, we focused on PRR sensing and signaling functions in the avian species, domestic chicken, mallard, and domestic goose. In addition to summarizing recent advances in the understanding of avian PRR functions, the present review utilized a comparative biology approach to identify additional PRRs, whose functions have been well studied in mammalians but await functional characterization in avian.

Adaptation of the Newcastle Disease Virus to Cell Cultures for Enhancing Its Oncolytic Properties

This study focuses on the adaptation of natural Newcastle disease virus (NDV) strains isolated from wild birds to human tumor cells. Many candidates for virotherapy are viruses pathogenic for human. During recombination of genetic material, there always exists a risk of getting a virus with an unstable genome. This problem can be solved by using natural apathogenic viruses as oncolytic agents. The Newcastle disease virus is the causative agent of contagious avian diseases. Its natural strains exhibit an antitumor effect and are considered safe for humans. As shown in earlier studies, the oncolytic properties of natural strains can be enhanced during adaptation to cell cultures, without interference in the virus genome. This study demonstrates that serial passaging increases the viral infectious titer in cancer cells. Moreover, the viability of tumor cells decreases post-infection when Newcastle disease virus strains are adapted to these cell cultures. The findings of this study complement the well-known data on the adaptation of the Newcastle disease virus to human cancer cells. Hence, it is possible to obtain a NDV strain with a more pronounced oncolytic potential during adaptation. This should be taken into account when choosing a strategy for designing anticancer drugs based on this virus.

Defects in interferon pathways as potential biomarkers of sensitivity to oncolytic viruses

Increased sensitivity of cancer cells to viruses is a prerequisite for the success of oncolytic virotherapy. One of the major causes of such a phenotype is the disruption of innate antiviral defenses associated with dysfunction of type 1 interferons (IFNs) that permits unlimited replication of viruses in cancer cells. Defects in IFN pathways help cancer progression by providing additional advantages to tumor cells. However, while these defects promote the survival and accelerated proliferation of malignant cells, they facilitate viral replication and thus enhance the efficiency of viral oncolysis. This review describes a broad spectrum of defects in genes that participate in IFN induction and IFN response pathways. Expression levels and/or functional activities of these genes are frequently low or absent in cancer cells, making them sensitive to virus infection. Therefore, certain specific defects in IFN signaling cascades might serve as potential biomarkers to help in identifying individual cancer patients who are likely to benefit from oncolytic virotherapy.

Proinflammatory response induced by Newcastle disease virus in tumor and normal cells

Purpose

To investigate the specific role of immune responses induced by lentogenic Newcastle disease virus (NDV) for its antitumor effect.

Materials and methods

NDV LaSota strain was used to infect the following human cells: non-small cell lung carcinoma (A549), glioblastoma (U87MG and T98G), mammary gland adenocarcinoma (MCF7 and MDA-MB-453), hepatocellular carcinoma (Huh7), transformed embryonic kidney cells (HEK293), primary monocytes, lung fibroblast (HF19), skin fibroblast (NB1RGB) and rat astroglia (RCR-1) at 0.001 multiplicity of infection. NDV-induced cytotoxicity and expression of proinflammatory cytokines were analyzed using 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide assay and multiplex enzyme-linked immunosorbent assay, respectively.

Results

Tumor cells (A549, U87MG, T98G, Huh7, MDA-MB-453, and MCF7) showed viability of <44%, while normal cell lines HEK293, NB1RGB, and RCR-1 showed 84%, 73%, and 69% viability at 72 hours postinfection, respectively. Proinflammatory cytokine profiling showed that NDV mainly induced the secretion of interferon (IFN)-α, IFN-β, and IFN-λ in tumor cells and only IFN-λ in normal cells. In addition, NDV infection induced the production of interleukin (IL)-6 in most cells.

Conclusion

Our findings suggest a new perspective regarding the role of IFN-λ and IL-6 in the mechanism of tumor selectivity and oncolysis of NDV.

Type I Interferon response in olfactory bulb, the site of tick-borne flavivirus accumulation, is primarily regulated by IPS-1

BACKGROUND

Although type I interferons (IFNs)-key effectors of antiviral innate immunity are known to be induced via different pattern recognition receptors (PRRs), the cellular source and the relative contribution of different PRRs in host protection against viral infection is often unclear. IPS-1 is a downstream adaptor for retinoid-inducible gene I (RIG-I)-like receptor signaling. In this study, we investigate the relative contribution of IPS-1 in the innate immune response in the different brain regions during infection with tick-borne encephalitis virus (TBEV), a flavivirus that causes a variety of severe symptoms like hemorrhagic fevers, encephalitis, and meningitis in the human host.

METHODS

IPS-1 knockout mice were infected with TBEV/Langat virus (LGTV), and viral burden in the peripheral and the central nervous systems, type I IFN induction, brain infiltrating cells, and inflammatory response was analyzed.

RESULTS

We show that IPS-1 is indispensable for controlling TBEV and LGTV infections in the peripheral and central nervous system. Our data indicate that IPS-1 regulates neuropathogenicity in mice. IFN response is differentially regulated in distinct regions of the central nervous system (CNS) influencing viral tropism, as LGTV replication was mainly restricted to olfactory bulb in wild-type (WT) mice. In contrast to the other brain regions, IFN upregulation in the olfactory bulb was dependent on IPS-1 signaling. IPS-1 regulates basal levels of antiviral interferon-stimulated genes (ISGs) like viperin and IRF-1 which contributes to the establishment of early viral replication which inhibits STAT1 activation. This diminishes the antiviral response even in the presence of high IFN-β levels. Consequently, the absence of IPS-1 causes uncontrolled virus replication, in turn resulting in apoptosis, activation of microglia and astrocytes, elevated proinflammatory response, and recruitment of inflammatory cells into the CNS.

CONCLUSIONS

We show that LGTV replication is restricted to the olfactory bulb and that IPS-1 is a very important player in the olfactory bulb in shaping the innate immune response by inhibiting early viral replication and viral spread throughout the central nervous system. In the absence of IPS-1, higher viral replication leads to the evasion of antiviral response by inhibiting interferon signaling. Our data suggest that the local microenvironment of distinct brain regions is critical to determine virus permissiveness.

Oncolytic Viruses: Exploiting Cancer's Deal with the Devil

Tumor cells harbor tens to thousands of genetic and epigenetic alterations that disrupt cellular pathways, providing them with growth and survival advantages. However, these benefits come at a cost, with uncontrolled cell growth, defective apoptosis, sustained pathological angiogenesis, immune evasion, and a metastatic phenotype occurring at the expense of the antiviral response of the individual tumor cell. Oncolytic virotherapy is an emerging therapeutic strategy that uses replication-competent viruses to selectivity kill cancer cells by exploiting their impaired antiviral response. In this review, we outline our understanding of the alterations in signaling pathways that simultaneously contribute to the malignant phenotype and virus-mediated killing of cancer cells.

Antineoplastic activity of Newcastle disease virus strain D90 in oral squamous cell carcinoma

Newcastle disease virus (NDV), an avian paramyxovirus, possesses the ability to kill tumor cells. Here, we report the effects of NDV strain D90, which was isolated in China, against oral squamous cell carcinoma (OSCC) cells. In this study, we showed that the cell death induced by D90 was apoptotic. Furthermore, the apoptosis induced by D90 was dependent on the mitochondrial pathway, and the death receptor pathway may be not involved. Bax and Bcl-2 also played a role in the apoptosis induced by D90. Lymph node metastasis is a serious problem for oral cancer; we therefore evaluated the impact of D90 on the migration and invasion of OSCC cells. NDV D90 affected microtubules and microfilaments to inhibit the motility of OSCC prior to apoptosis. The effects of D90 on the migration and invasion rates of OSCC cells were evaluated by migration and invasion assays. Subsequently, the changes in sp1, RECK, MMP-2, and MMP-9 induced by a low concentration of D90 were detected by western blot and gelatin zymography. D90 significantly inhibited the invasion and metastasis of OSCC cells by decreasing the expression of sp1 and increasing the expression of RECK to suppress the expression and activity of MMP-2 and MMP-9.

IPS-1 differentially induces TRAIL, BCL2, BIRC3 and PRKCE in type I interferons-dependent and -independent anticancer activity

RIG-I-like receptors are the key cytosolic sensors for RNA viruses and induce the production of type I interferons (IFN) and pro-inflammatory cytokines through a sole adaptor IFN-β promoter stimulator-1 (IPS-1) (also known as Cardif, MAVS and VISA) in antiviral innate immunity. These sensors also have a pivotal role in anticancer activity through induction of apoptosis. However, the mechanism for their anticancer activity is poorly understood. Here, we show that anticancer vaccine adjuvant, PolyIC (primarily sensed by MDA5) and the oncolytic virus, Newcastle disease virus (NDV) (sensed by RIG-I), induce anticancer activity. The ectopic expression of IPS-1 into type I IFN-responsive and non-responsive cancer cells induces anticancer activity. PolyIC transfection and NDV infection upregulate pro-apoptotic gene TRAIL and downregulate the anti-apoptotic genes BCL2, BIRC3 and PRKCE. Furthermore, stable knockdown of IPS-1, IRF3 or IRF7 in IFN-non-responsive cancer cells show reduced anticancer activity by suppressing apoptosis via TRAIL and anti-apoptotic genes. Collectively, our study shows that IPS-1 induces anticancer activity through upregulation of pro-apoptotic gene TRAIL and downregulation of the anti-apoptotic genes BCL2, BIRC3 and PRKCE via IRF3 and IRF7 in type I IFN-dependent and -independent manners.

Autonomous parvoviruses neither stimulate nor are inhibited by the type I interferon response in human normal or cancer cells

Members of the genus Parvovirus are small, nonenveloped single-stranded DNA viruses that are nonpathogenic in humans but have potential utility as cancer therapeutics. Because the innate immune response to parvoviruses has received relatively little attention, we compared the response to parvoviruses to that of several other types of viruses in human cells. In normal human glia, fibroblasts, or melanocytes, vesicular stomatitis virus evoked robust beta interferon (IFN-β) responses. Cytomegalovirus, pseudorabies virus, and Sindbis virus all evoked a 2-log-unit or greater upregulation of IFN-β in glia; in contrast, LuIII and MVMp parvoviruses did not evoke a detectable IFN-β or interferon-stimulated gene (ISG; MX1, oligoadenylate synthetase [OAS], IFIT-1) response in the same cell types. The lack of response raised the question of whether parvoviral infection can be attenuated by IFN; interestingly, we found that IFN did not decrease parvovirus (MVMp, LuIII, and H-1) infectivity in normal human glia, fibroblasts, or melanocytes. The same was true in human cancers, including glioma, sarcoma, and melanoma. Similarly, IFN failed to attenuate transduction by the dependovirus vector adeno-associated virus type 2. Progeny production of parvoviruses was also unimpaired by IFN in both glioma and melanoma, whereas vesicular stomatitis virus replication was blocked. Sarcoma cells with upregulated IFN signaling that show high levels of resistance to other viruses showed strong infection by LuIII. Unlike many other oncolytic viruses, we found no evidence that impairment of innate immunity in cancer cells plays a role in the oncoselectivity of parvoviruses in human cells. Parvoviral resistance to the effects of IFN in cancer cells may constitute an advantage in the virotherapy of some tumors.

IMPORTANCE

Understanding the interactions between oncolytic viruses and the innate immune system will facilitate employing these viruses as therapeutic agents in cancer patients. The cancer-selective nature of some oncolytic viruses is based on the impaired innate immunity of many cancer cells. The parvoviruses H-1, LuIII, and MVM target cancer cells; however, their relationship with the innate immune system is relatively uncharacterized. Surprisingly, we found that these parvoviruses do not evoke an interferon response in normal human fibroblasts, glia, or melanocytes. Furthermore, unlike most other types of virus, we found that parvovirus infectivity is unaffected by interferon treatment of human normal or tumor cells. Finally, parvoviral replication was unimpaired by interferon in four human tumor types, including those with residual interferon functionality. We conclude that deficits in the interferon antiviral response of cancer cells do not contribute to parvoviral oncoselectivity in human cells. The interferon-resistant phenotype of parvoviruses may give them an advantage over interferon-sensitive oncolytic viruses in tumors showing residual interferon functionality.

Different responses of human pancreatic adenocarcinoma cell lines to oncolytic Newcastle disease virus infection

Newcastle disease virus (NDV) is a naturally occurring oncolytic virus with clinically proven efficacy against several human tumor types. Selective replication in and killing of tumor cells by NDV is thought to occur because of differences in innate immune responses between normal and tumor cells. In our effort to develop oncolytic virotherapy with NDV for patients with pancreatic cancer, we evaluated the responses to NDV infection and interferon (IFN) treatment of 11 different established human pancreatic adenocarcinoma cell lines (HPACs). Here we show that all HPACs were susceptible to NDV. However, this NDV infection resulted in different replication kinetics and cytotoxic effects. Better replication resulted in more cytotoxicity. No correlation was observed between defects in the IFN pathways and NDV replication or NDV-induced cytotoxicity. IFN production by HPACs after NDV infection differed substantially. Pretreatment of HPACs with IFN resulted in diminished NDV replication and decreased the cytotoxic effects in most HPACs. These findings suggest that not all HPACs have functional defects in the innate immune pathways, possibly resulting in resistance to oncolytic virus treatment. These data support the rationale for designing recombinant oncolytic NDVs with optimized virulence that should likely contain an antagonist of the IFN pathways.

Prostate-specific antigen-retargeted recombinant newcastle disease virus for prostate cancer virotherapy

Oncolytic virus (OV) therapies of cancer are based on the use of replication-competent, tumor-selective viruses with limited toxicity. Newcastle disease virus (NDV), an avian paramyxovirus, is a promising OV and is inherently tumor selective and cytotoxic only to tumor cells. Replication is restricted in normal cells. Despite encouraging phase I/II clinical trials with NDV, further refinements for tumor-specific targeting are needed to enhance its therapeutic index. Systemically delivered NDV fails to reach solid tumors in therapeutic concentrations and also spreads poorly within the tumors due to barriers including complement, innate immunity, and the extracellular matrix. Overcoming these hurdles is paramount to realizing the exceptional oncolytic efficacy of NDV. We engineered the F protein of NDV and generated a recombinant NDV (rNDV) whose F protein is cleavable exclusively by prostate-specific antigen (PSA). The rNDV replicated efficiently and specifically in prostate cancer (CaP) cells and 3-dimensional prostaspheres but failed to replicate in the absence of PSA. Induction of intracellular PSA production by a synthetic androgen analog (R1881) enhanced fusogenicity in androgen-responsive CaP cells. Further, PSA-cleavable rNDV caused specific lysis of androgen-independent and androgen-responsive/nonresponsive CaP cells and prostaspheres, with a half-maximal effective concentration (EC50) ranging from a multiplicity of infection of 0.01 to 0.1. PSA-retargeted NDV efficiently lysed prostasphere tumor mimics, suggesting efficacy in vivo. Also, PSA-cleavable NDV failed to replicate in chicken embryos, indicating no pathogenicity for chickens. Prostate-specific antigen targeting is likely to enhance the therapeutic index of rNDV owing to tumor-restricted replication and enhanced fusogenicity.