Long-Lasting Protection Induced by a Polyanhydride Nanovaccine against Respiratory Syncytial Virus in an Outbred Mouse Model.

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in children. In humans, natural infection with RSV affords only partial long-term protection from reinfection, and there is no licensed RSV vaccine currently available. We have developed a new vaccine candidate, termed RSVNanoVax, composed of polyanhydride nanoparticles encapsulating the RSV prefusion F protein and a CpG 1668 oligodeoxynucleotide adjuvant. We recently reported that vaccination of inbred BALB/c mice with RSVNanoVax induced both RSV-specific cellular and humoral immunity, which provided protection from viral replication and RSV-induced disease. To further assess the efficacy of RSVNanoVax, here, we utilized outbred Swiss Webster mice to examine vaccine efficacy in a more genetically diverse population. Following intranasal prime-boost vaccination with RSVNanoVax, Swiss Webster mice exhibited robust titers of systemic RSV F-directed IgG antibodies and RSV F-directed IgA within the lungs and nasal passages that were sustained out to at least 1 year post-vaccination. Serum antibodies maintained robust neutralizing activity against both RSV A and B strains. Following RSV challenge, vaccinated Swiss Webster mice exhibited rapid viral clearance from the lungs. Overall, our results indicate that RSVNanoVax represents a promising RSV vaccine candidate capable of providing long-term protection and immunity in a genetically diverse population. IMPORTANCE Respiratory syncytial virus (RSV) infection causes thousands of infections and deaths in children and elderly adults each year. Research in this field is of great importance as there remains no licensed vaccine to prevent RSV infections. We developed a novel vaccine candidate, RSVNanoVax, utilizing the RSV prefusion F protein encapsulated in polyanhydride nanoparticles. Here, we show that the intranasal delivery of RSVNanoVax protected outbred mice from viral replication within the lungs when challenged with RSV out to 1 year post-vaccination. Additionally, RSV-specific antibody responses were generated in both the serum and lung tissue and sustained long-term. These results demonstrate that our vaccine is an encouraging candidate for driving long-term protection in the lungs in a genetically diverse population.

Prefusion F-Based Polyanhydride Nanovaccine Induces Both Humoral and Cell-Mediated Immunity Resulting in Long-Lasting Protection against Respiratory Syncytial Virus.

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection in both young children and in older adults. Despite the morbidity, mortality, and high economic burden caused by RSV worldwide, no licensed vaccine is currently available. We have developed a novel RSV vaccine composed of a prefusion-stabilized variant of the fusion (F) protein (DS-Cav1) and a CpG oligodeoxynucleotide adjuvant encapsulated within polyanhydride nanoparticles, termed RSVNanoVax. A prime-boost intranasal administration of RSVNanoVax in BALB/c mice significantly alleviated weight loss and pulmonary dysfunction in response to an RSV challenge, with protection maintained up to at least 6 mo postvaccination. In addition, vaccinated mice exhibited rapid viral clearance in the lungs as early as 2 d after RSV infection in both inbred and outbred populations. Vaccination induced tissue-resident memory CD4 and CD8 T cells in the lungs, as well as RSV F-directed neutralizing Abs. Based on the robust immune response elicited and the high level of durable protection observed, our prefusion RSV F nanovaccine is a promising new RSV vaccine candidate.

Immune Autoregulatory CD8 T Cells Require IFN-γ Responsiveness to Optimally Suppress Central Nervous System Autoimmunity.

Investigating the complex cellular interplay controlling immunopathogenic and immunoregulatory responses is critical for understanding multiple sclerosis (MS) and for developing successful immunotherapies. Our group has demonstrated that CNS myelin-specific CD8 T cells unexpectedly harbor immune regulatory capacity in both mouse and human. In particular, PLP178-191-specific CD8 T cells (PLP-CD8) robustly suppress the MS mouse model experimental autoimmune encephalomyelitis. We have recently shown that this depends on PLP-CD8 elaborating IFN-γ and perforin in a coordinated suppression program over time. However, the cellular target and downstream effects of CD8 T cell-derived IFN-γ remains poorly understood. In this study, we show that although wild-type (WT) PLP-CD8 were robustly suppressive in IFN-γR-deficient mice, IFN-γR-deficient PLP-CD8 exhibited suboptimal suppression in WT mice. Compared with WT counterparts, IFN-γR-deficient PLP-CD8 were defective in suppressing disease in IFN-γ-deficient recipients, a scenario in which the only IFN-γ available to WT PLP-CD8 is that which they produce themselves. Further, we found that IFN-γR-deficient PLP-CD8 exhibited altered granzyme/IFN-γ profiles, altered migration in recipients, and deficits in killing capacity in vivo. Collectively, this work suggests that IFN-γ responsiveness allows myelin-specific CD8 T cells to optimally perform autoregulatory function in vivo. These insights may help elucidate future adoptive immunotherapeutic approaches for MS patients.

Pharmacological ascorbate as a novel therapeutic strategy to enhance cancer immunotherapy.

Pharmacological ascorbate (i.e., intravenous infusions of vitamin C reaching ~ 20 mM in plasma) is under active investigation as an adjuvant to standard of care anti-cancer treatments due to its dual redox roles as an antioxidant in normal tissues and as a prooxidant in malignant tissues. Immune checkpoint inhibitors (ICIs) are highly promising therapies for many cancer patients but face several challenges including low response rates, primary or acquired resistance, and toxicity. Ascorbate modulates both innate and adaptive immune functions and plays a key role in maintaining the balance between pro and anti-inflammatory states. Furthermore, the success of pharmacological ascorbate as a radiosensitizer and a chemosensitizer in pre-clinical studies and early phase clinical trials suggests that it may also enhance the efficacy and expand the benefits of ICIs.

Pharmacological ascorbate improves the response to platinum-based chemotherapy in advanced stage non-small cell lung cancer.

PURPOSE: Platinum-based chemotherapy with or without immunotherapy is the mainstay of treatment for advanced stage non-small cell lung cancer (NSCLC) lacking a molecular driver alteration. Pre-clinical studies have reported that pharmacological ascorbate (P-AscH-) enhances NSCLC response to platinum-based therapy. We conducted a phase II clinical trial combining P-AscH- with carboplatin-paclitaxel chemotherapy. EXPERIMENTAL DESIGN: Chemotherapy naïve advanced stage NSCLC patients received 75 g ascorbate twice per week intravenously with carboplatin and paclitaxel every three weeks for four cycles. The primary endpoint was to improve tumor response per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 compared to the historical control of 20%. The trial was conducted as an optimal Simon's two-stage design. Blood samples were collected for exploratory analyses. RESULTS: The study enrolled 38 patients and met its primary endpoint with an objective response rate of 34.2% (p = 0.03). All were confirmed partial responses (cPR). The disease control rate was 84.2% (stable disease + cPR). Median progression-free and overall survival were 5.7 months and 12.8 months, respectively. Treatment-related adverse events (TRAE) included one grade 5 (neutropenic fever) and five grade 4 events (cytopenias). Cytokine and chemokine data suggest that the combination elicits an immune response. Immunophenotyping of peripheral blood mononuclear cells demonstrated an increase in effector CD8 T-cells in patients with a progression-free survival (PFS) ≥ 6 months. CONCLUSIONS: The addition of P-AscH- to platinum-based chemotherapy improved tumor response in advanced stage NSCLC. P-AscH- appears to alter the host immune response and needs further investigation as a potential adjuvant to immunotherapy.

Considerations for a Respiratory Syncytial Virus Vaccine Targeting an Elderly Population.

Respiratory syncytial virus (RSV) is most commonly associated with acute lower respiratory tract infections in infants and children. However, RSV also causes a high disease burden in the elderly that is often under recognized. Adults >65 years of age account for an estimated 80,000 RSV-associated hospitalizations and 14,000 deaths in the United States annually. RSV infection in aged individuals can result in more severe disease symptoms including pneumonia and bronchiolitis. Given the large disease burden caused by RSV in the aged, this population remains an important target for vaccine development. Aging results in lowered immune responsiveness characterized by impairments in both innate and adaptive immunity. This immune senescence poses a challenge when developing a vaccine targeting elderly individuals. An RSV vaccine tailored towards an elderly population will need to maximize the immune response elicited in order to overcome age-related defects in the immune system. In this article, we review the hurdles that must be overcome to successfully develop an RSV vaccine for use in the elderly, and discuss the vaccine candidates currently being tested in this highly susceptible population.

Function and Modulation of Type I Interferons during Respiratory Syncytial Virus Infection.

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory infections in infants and young children, accounting for an estimated 3 million hospitalizations annually worldwide. Despite the major health burden, there is currently no licensed RSV vaccine. RSV is recognized by a range of cellular receptors including both toll-like receptors (TLR) and retinoic acid-inducible gene-I-like receptors (RIG-I). This interaction initiates signaling through mitochondrial antiviral signaling (MAVS) and interferon regulatory factor (IRF) proteins, resulting in the induction of type I interferons (IFN). Early viral control is mediated by either IFN-α or IFN-ß signaling through the IFN receptor (IFNAR), inducing the production of antiviral interferon-stimulating genes (ISGs). Type I IFNs also initiate the early production of proinflammatory cytokines including interleukin 6 (IL-6), tumor necrosis factor (TNF), and IFN-γ. Type I IFN levels correlate with age, and inadequate production may be a critical factor in facilitating the increased RSV disease severity observed in infants. Here, we review the current literature on the function of type I IFNs in RSV pathogenesis, as well as their involvement in the differential immune responses observed in infants and adults.

Nanoparticle vaccines against respiratory syncytial virus.

Respiratory syncytial virus (RSV) is a leading cause of respiratory disease in infants, the elderly and immunocompromised individuals. Despite the global burden, there is no licensed vaccine for RSV. Recent advances in the use of nanoparticle technology have provided new opportunities to address some of the limitations of conventional vaccines. Precise control over particle size and surface properties enhance antigen stability and prolong antigen release. Particle size can also be modified to target specific antigen-presenting cells in order to induce specific types of effector T-cell responses. Numerous nanoparticle-based vaccines are currently being evaluated for RSV including inorganic, polymeric and virus-like particle-based formulations. Here, we review the potential advantages of using different nanoparticle formulations in a vaccine for RSV, and discuss many examples of safe, and effective vaccines currently in both preclinical and clinical stages of testing.