ABSTRACT
Background: Currently available COVID-19 vaccination regimens in the US deliver either a homologous spike (S) mRNA prime-boost or a prime-only S DNA adenovirus-vectored antigen to elicit humoral and cell-mediated responses to confer protection against SAR-CoV-2 infection. Alternatively, heterologous vaccination using two different platforms has the potential to enhance and expand immune protection. Addition of a second SARS-CoV-2 antigen, the nucleocapsid (N) protein that is less subject to mutation and elicits vigorous T-cell responses, may also be advantageous. We report immunological responses to homologous and heterologous prime-boost vaccination regimens with a human DNA adenovirus serotype 5 S plus N (AdS+N) and/or a self-amplifying S-only mRNA vaccine (AAAH) delivered with a nanostructured lipid carrier (NLC). Methods: CD-1 mice received homologous or heterologous prime-boost combinations of AdS+N and AAAH. Priming doses were administered on Day 0, booster doses were delivered on Day 21, and mice were euthanized for blood and organ collection on Day 35. Serum was analyzed for anti-S (both wild type and variant) and anti-N IgG subtypes by ELISA. Spleen-resident CD4+ and CD8+ T cells were tested for IFN-γ, TNF-α, and IL-2 production in response to S-WT, S Delta variant and N protein overlapping peptides by intracellular cytokine staining (ICS). Splenocyte cytokine secretion upon stimulation with S-WT/N peptides was also assessed by IFN-γ and IL-4 ELISpot. Serum neutralization of the original Wuhan strain, Delta, and B.1.351 variants was assessed by a pseudovirus neutralization assay. Results: The highest humoral and T-cell responses were seen with the heterologous AAAH prime-AdS+N boost regimen, with a significant increase in T-cell responses relative to homologous vaccination. S protein-binding IgG was similar between wild type and Delta variant S proteins, with a strong/clear Th1/Th2 bias, and T cells responded to S wild type and S Delta peptides with similar levels of cytokine expression. Sera from AAAH prime-AdS+N boost mice showed the ability to neutralize Wuhan D614G, Delta, and B.1.351 (South Africa) variant pseudoviruses at high levels. Conclusion: Heterologous vaccination with the AAAH RNA vaccine prime and an AdS+N DNA boost may provide substantially improved humoral and cell-based immunity against SARS-CoV-2 variants by leveraging the advantages of each vaccine platform technology and by inclusion of immune responses to N.
ABSTRACT
Lipid nanoparticles (LNPs) are gaining traction in the field of nucleic acid delivery following the success of two mRNA vaccines against COVID-19. As one of the constituent lipids on LNP surfaces, PEGylated lipids (PEG-lipids) play an important role in defining LNP physicochemical properties and biological interactions. Previous studies indicate that LNP performance is modulated by tuning PEG-lipid parameters including PEG size and architecture, carbon tail type and length, as well as the PEG-lipid molar ratio in LNPs. Owing to these numerous degrees of freedom, a high-throughput approach is necessary to fully understand LNP behavioral trends over a broad range of PEG-lipid variables. To this end, we report a low-volume, automated, high-throughput screening (HTS) workflow for the preparation, characterization, and in vitro assessment of LNPs loaded with a therapeutic antisense oligonucleotide (ASO). A library of 54 ASO-LNP formulations with distinct PEG-lipid compositions was prepared using a liquid handling robot and assessed for their physiochemical properties as well as gene silencing efficacy in murine cortical neurons. Our results show that the molar ratio of anionic PEG-lipid in LNPs regulates particle size and PEG-lipid carbon tail length controls ASO-LNP gene silencing activity. ASO-LNPs formulated using PEG-lipids with optimal carbon tail lengths achieved up to 5-fold lower mRNA expression in neurons as compared to naked ASO. Representative ASO-LNP formulations were further characterized using dose-response curves and small-angle X-ray scattering to understand structure-activity relationships. Identified hits were also tested for efficacy in primary murine microglia and were scaled-up using a microfluidic formulation technique, demonstrating a smooth translation of ASO-LNP properties and in vitro efficacy. The reported HTS workflow can be used to screen additional multivariate parameters of LNPs with significant time and material savings, therefore guiding the selection and scale-up of optimal formulations for nucleic acid delivery to a variety of cellular targets.
ABSTRACT
Castleman Disease (CD) represents a group of rare and heterogeneous hematologic disorders that have common lymph node histopathology. Patients with CD are often immunosuppressed as a consequence of immunemodulating therapy or possibly due to an underlying immunologic dysfunction attributable to B-cell dysfunction. The most severe CD cases experience a cytokine storm disorder, a life-threatening exacerbation of circulating cytokines and immune-cell hyperactivation. Infection with SARS-CoV-2 progresses to a severe cytokine storm in the most severe cases of COVID-19. Interleukin-6 (IL-6) is central to the pathogenesis of CD, and increased IL-6 often accompanies severe COVID-19 cases;inhibition of IL-6 with monoclonal antibodies has been shown to be effective therapy for both CD and severe COVID-19. We therefore sought to understand the impact of COVID-19 infection on the natural history of CD and also examined the safety and tolerability of COVID-19 vaccines in this vulnerable patient population. Patients enrolled in a longitudinal natural history study of CD (N=298) were invited to participate in a survey designed to characterize their experience with COVID-19 disease and vaccination. Surveys were emailed to all eligible patients, and reminders were sent up to 3 times. All data is self-reported;descriptive analyses are reported herein. Of the 298 patients who received a survey, 101 (33.9%) completed it. Sixty-nine (68%) had been tested for SARS-CoV-2 at least once, and 10 (14.5%) reported testing positive - including 6 UCD, 3 iMCD, and 1 HHV8+ MCD patients. The reported prevalence of SARS-CoV-2 infection in the US compares at 10.5%. Two of the 10 patients reported asymptomatic disease (both UCD), 7 reported mild disease (4 UCD, 1 iMCD, 1 HHV8+MCD), and 1 reported moderate disease requiring hospitalization but not a ventilator or intensive care (iMCD). This severity distribution suggests that these potentially immunocompromised patients experience a range of disease severity consistent with SARS-CoV-2 infection in the broader US population. The most commonly-reported symptoms included fevers/chills, headaches, and loss of taste or smell (N=7 each), as well as shortness of breath/difficulty breathing, muscle and body aches, and cough (N=5 each). Rarer symptoms were also noted among the iMCD patients, including discoloration of skin, lips, or nailbeds (N=1) and newfound confusion (N=2). Two of the 10 patients reported stopping siltuximab treatment during their COVID-19 diagnosis;both subsequently resumed treatment. No other treatment changes were reported. Of the 101 respondents, 87 (86%) had received at least 1 vaccine dose. Treatments, such as immunosuppressants and immunomodulators, were paused for 7 of these patients including, during the vaccination period;this was presumably done to increase the likelihood of a robust response to the vaccine. Fifty-one patients (59%) reported side effects to either dose 1 or 2. Side effects were generally mild, and none required hospitalization. Side effects were more commonly reported after dose 2, with the most common being arm pain (N=34), fatigue (N=30), and headache (N=26). Of those who reported not receiving the vaccine, 2 intend to receive it in the future, 5 reported being unsure about receiving it, and 7 do not intend to receive the vaccine. Common concerns include potential interaction with CD (N=9) and limited safety data (N=8). This study represents the first investigation into the experience of CD patients with SARS-CoV-2 testing, diagnosis, and vaccination. We did not observe a markedly increased inflammatory response to SARS-CoV-2 infection, and vaccination was well-tolerated. A limitation is self-selection survey bias;it is possible that those who chose to participate represent those who had a milder reaction in general. However, it is noteworthy that there were no reports of severe disease in this sample. The prevalence of confirmed SARS-CoV-2 infection in this cohort (14.5%) is marginally higher than reported in the US population (10.5%) but statistical comp risons were not performed given that this study does not provide a general epidemiological estimate. However, the distribution of symptoms and vaccine adverse effects in this sample were comparable to the general population. Though additional follow-up is planned for the future, these data are an important basis for understanding the interaction of SARS-CoV-2 and CD. Disclosures: Casper: EUSA Pharma: Consultancy. Fajgenbaum: Pfizer: Other: Study drug for clinical trial of sirolimus;N/A: Other: Holds pending provisional patents for ‘Methods of treating idiopathic multicentric Castleman disease with JAK1/2 inhibition’ and ‘Discovery and validation of a novel subgroup and therapeutic target in idiopathic multicentric Castleman disease’;EUSA Pharma: Research Funding. OffLabel Disclosure: Our makes reference to the following: “Interleukin-6 (IL-6) is central to the pathogenesis of CD, and increased IL-6 often accompanies severe COVID-19 cases;inhibition of IL-6 with monoclonal antibodies has been shown to be effective therapy for both CD and severe COVID-19.” Inhibition of IL-6 with monoclonal antibodies for use in COVID-19 is off-label.