Sequence and tissue targeting specificity of ZFP36L2 reveals Elavl2 as a novel target with co-regulation potential

Zinc finger protein 36 like 2 (ZFP36L2) is an RNA-binding protein that destabilizes transcripts containing adenine-uridine rich elements (AREs). The overlap between ZFP36L2 targets in different tissues is minimal, suggesting that ZFP36L2-targeting is highly tissue specific. We developed a novel Zfp36l2-lacking mouse model (L2-fKO) to identify factors governing this tissue specificity. We found 549 upregulated genes in the L2-fKO spleen by RNA-seq. These upregulated genes were enriched in ARE motifs in the 3′UTRs, which suggests that they are ZFP36L2 targets, however the precise sequence requirement for targeting was not evident from motif analysis alone. We therefore used gel-shift mobility assays on 12 novel putative targets and established that ZFP36L2 requires a 7-mer (UAUUUAU) motif to bind. We observed a statistically significant enrichment of 7-mer ARE motifs in upregulated genes and determined that ZFP36L2 targets are enriched for multiple 7-mer motifs. Elavl2 mRNA, which has three 7-mer (UAUUUAU) motifs, was also upregulated in L2-fKO spleens. Overexpression of ZFP36L2, but not a ZFP36L2(C176S) mutant, reduced Elavl2 mRNA expression, suggesting a direct negative effect. Additionally, a reporter assay demonstrated that the ZFP36L2 effect on Elavl2 decay is dependent on the Elavl2-3′UTR and requires the 7-mer AREs. Our data indicate that Elavl2 mRNA is a novel target of ZFP36L2, specific to the spleen. Likely, ZFP36L2 combined with other RNA binding proteins, such as ELAVL2, governs tissue specificity.

A model of persistent post SARS-CoV-2 induced lung disease for target identification and testing of therapeutic strategies

COVID-19 survivors develop post-acute sequelae of SARS-CoV-2 (PASC), but the mechanistic basis of PASC-associated lung abnormalities suffers from a lack of longitudinal samples. Mouse-adapted SARS-CoV-2 MA10 produces an acute respiratory distress syndrome (ARDS) in mice similar to humans. To investigate PASC pathogenesis, studies of MA10-infected mice were extended from acute disease through clinical recovery. At 15-120 days post-virus clearance, histologic evaluation identified subpleural lesions containing collagen, proliferative fibroblasts, and chronic inflammation with tertiary lymphoid structures. Longitudinal spatial transcriptional profiling identified global reparative and fibrotic pathways dysregulated in diseased regions, similar to human COVID-19. Populations of alveolar intermediate cells, coupled with focal upregulation of pro-fibrotic markers, were identified in persistently diseased regions. Early intervention with antiviral EIDD-2801 reduced chronic disease, and early anti-fibrotic agent (nintedanib) intervention modified early disease severity. This murine model provides opportunities to identify pathways associated with persistent SARS-CoV-2 pulmonary disease and test countermeasures to ameliorate PASC.

Update on the Features and Measurements of Experimental Acute Lung Injury in Animals: An Official American Thoracic Society Workshop Report

Advancements in methods, technology, and our understanding of the pathobiology of lung injury have created the need to update the definition of experimental acute lung injury (ALI). We queried 50 participants with expertise in ALI and acute respiratory distress syndrome using a Delphi method composed of a series of electronic surveys and a virtual workshop. We propose that ALI presents as a "multidimensional entity" characterized by four "domains" that reflect the key pathophysiologic features and underlying biology of human acute respiratory distress syndrome. These domains are 1) histological evidence of tissue injury, 2) alteration of the alveolar-capillary barrier, 3) presence of an inflammatory response, and 4) physiologic dysfunction. For each domain, we present "relevant measurements," defined as those proposed by at least 30% of respondents. We propose that experimental ALI encompasses a continuum of models ranging from those focusing on gaining specific mechanistic insights to those primarily concerned with preclinical testing of novel therapeutics or interventions. We suggest that mechanistic studies may justifiably focus on a single domain of lung injury, but models must document alterations of at least three of the four domains to qualify as "experimental ALI." Finally, we propose that a time criterion defining "acute" in ALI remains relevant, but the actual time may vary based on the specific model and the aspect of injury being modeled. The continuum concept of ALI increases the flexibility and applicability of the definition to multiple models while increasing the likelihood of translating preclinical findings to critically ill patients.

A mucoadhesive biodissolvable thin film for localized and rapid delivery of lidocaine for the treatment of vestibulodynia

Vestibulodynia (VBD), an idiopathic pain disorder characterized by erythema and pain of the vulvar vestibule (the inner aspect of the labia minora and vaginal opening), is the most common cause of sexual pain for women of reproductive age. Women also feel discomfort with contact with clothing and tampon use. As most women with this disorder only have pain with provocation of the tissue, topical anesthetics applied to the vestibule are the current first line treatment for temporary pain relief. Treatment options are limited due to anatomical constraints of the vestibular region, poor drug retention time, imprecise dosing, leakage, and overall product messiness. In this study we report a novel approach to treatment of VBD using thin film designed to fit the vulvar vestibule and deliver lidocaine locally. Two use cases for VBD treatment were identified 1) rapid drug release (<5 min), for use prior to intercourse and 2) long-acting release (≥120 min) for prolonged use and relief throughout the day. Cellulose-based mucoadhesive thin films were fabricated using a solvent casting method. Three polymers including hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), and hydroxypropylmethycellulose (HMPC), were selected owing to their biocompatibility and ideal properties for film casting. Films casted with HEC, HPC, and HPMC exhibited mucoadhesive properties relative to a control, with the highest mucoadhesive force recorded for films casted with HPC. Effect of media volume, pH, presence of mucin and presence of drug on film dissolution rates were investigated. Dissolution rates were independent of media volume, media pH or drug presence, whereas faster dissolution rates were obtained for all films in presence of mucin. In vitro lidocaine release kinetics were influenced by polymer type, percent drug loading and film casting thickness. Lidocaine release was based on a diffusion mechanism rather than through film dissolution and faster release (∼5 min) was observed for HEC films compared HPC films (∼120 min). Higher drug loading and film thickness resulted in slower and more prolonged release kinetics of lidocaine. All films were biocompatible and exhibited good mechanical properties. Two film formulations (9% w/w HPC with 12% w/w LHC, 5% w/w HEC with 6% w/w LHC) were optimized to meet the two use case scenarios for VBD treatment and moved into in vivo testing. In vivo testing demonstrated the safety of the films in BALB/c mice, and the pharmacokinetic analysis demonstrated the delivery of lidocaine primarily to the vaginal tissue. We demonstrate the ability to develop a mucoadhesive, biodissolvable thin film and fine-tune drug release kinetics to optimize local delivery of lidocaine to the vulva.

Myeloid Protease-Activated Receptor-2 Contributes to Influenza A Virus Pathology in Mice

Background

Innate immune responses to influenza A virus (IAV) infection are initiated in part by toll-like receptor 3 (TLR3). TLR3-dependent signaling induces an antiviral immune response and an NFκB-dependent inflammatory response. Protease-activated receptor 2 (PAR2) inhibits the antiviral response and enhances the inflammatory response. PAR2 deficiency protected mice during IAV infection. However, the PAR2 expressing cell-types contributing to IAV pathology in mice and the mechanism by which PAR2 contributes to IAV infection is unknown.

Methods

IAV infection was analyzed in global (Par2-/-), myeloid (Par2fl/fl;LysMCre+) and lung epithelial cell (EpC) Par2 deficient (Par2fl/fl;SPCCre+) mice and their respective controls (Par2+/+ and Par2fl/fl). In addition, the effect of PAR2 activation on polyinosinic-polycytidylic acid (poly I:C) activation of TLR3 was analyzed in bone marrow-derived macrophages (BMDM). Lastly, we determined the effect of PAR2 inhibition in wild-type (WT) mice.

Results

After IAV infection, Par2-/- and mice with myeloid Par2 deficiency exhibited increased survival compared to infected controls. The improved survival was associated with reduced proinflammatory mediators and reduced cellular infiltration in bronchoalveolar lavage fluid (BALF) of Par2-/- and Par2fl/fl;LysMCre+ 3 days post infection (dpi) compared to infected control mice. Interestingly, Par2fl/fl;SPCCre+ mice showed no survival benefit compared to Par2fl/fl. In vitro studies showed that Par2-/- BMDM produced less IL6 and IL12p40 than Par2+/+ BMDM after poly I:C stimulation. In addition, activation of PAR2 on Par2+/+ BMDM increased poly I:C induction of IL6 and IL12p40 compared to poly I:C stimulation alone. Importantly, PAR2 inhibition prior to IAV infection protect WT mice.

Conclusion

Global Par2 or myeloid cell but not lung EpC Par2 deficiency was associated with reduced BALF inflammatory markers and reduced IAV-induced mortality. Our study suggests that PAR2 may be a therapeutic target to reduce IAV pathology.

A broadly cross-reactive antibody neutralizes and protects against sarbecovirus challenge in mice

[Figure: see text].

Bioequivalence assessment of high-capacity polymeric micelle nanoformulation of paclitaxel and Abraxane® in rodent and non-human primate models using a stable isotope tracer assay

The in vivo fate of nanoformulated drugs is governed by the physicochemical properties of the drug and the functionality of nanocarriers. Nanoformulations such as polymeric micelles, which physically encapsulate poorly soluble drugs, release their payload into the bloodstream during systemic circulation. This results in three distinct fractions of the drug-nanomedicine: encapsulated, protein-bound, and free drug. Having a thorough understanding of the pharmacokinetic (PK) profiles of each fraction is essential to elucidate mechanisms of nanomedicine-driven changes in drug exposure and PK/PD relationships pharmacodynamic activity. Here, we present a comprehensive preclinical assessment of the poly (2-oxazoline)-based polymeric micelle of paclitaxel (PTX) (POXOL hl-PM), including bioequivalence comparison to the clinically approved paclitaxel nanomedicine, Abraxane®. Physicochemical characterization and toxicity analysis of POXOL hl-PM was conducted using standardized protocols by the Nanotechnology Characterization Laboratory (NCL). The bioequivalence of POXOL hl-PM to Abraxane® was evaluated in rats and rhesus macaques using the NCL's established stable isotope tracer ultrafiltration assay (SITUA) to delineate the plasma PK of each PTX fraction. The SITUA study revealed that POXOL hl-PM and Abraxane® had comparable PK profiles not only for total PTX but also for the distinct drug fractions, suggesting bioequivalence in given animal models. The comprehensive preclinical evaluation of POXOL hl-PM in this study showcases a series of widely applicable standardized studies by NCL for assessing nanoformulations prior to clinical investigation.

Mouse Models for the Study of SARS-CoV-2 Infection

Mice are an invaluable resource for studying virus-induced disease. They are a small, genetically modifiable animal for which a large arsenal of genetic and immunologic tools is available for evaluation of pathogenesis and potential vaccines and therapeutics. SARS-CoV-2, the betacoronavirus responsible for the COVID-19 pandemic, does not naturally replicate in wild-type mice, due to structural differences between human and mouse ACE2, the primary receptor for SARS-CoV-2 entry into cells. However, several mouse strains have been developed that allow for SARS-CoV-2 replication and clinical disease. Two broad strategies have primarily been deployed for developing mouse strains susceptible to COVID-19-like disease: adding in the human ACE2 gene and adapting the virus to the mouse ACE2 receptor. Both approaches result in mice that develop several of the clinical and pathologic hallmarks of COVID-19, including acute respiratory distress syndrome and acute lung injury. In this review, we describe key acute pulmonary and extrapulmonary pathologic changes seen in COVID-19 patients that mouse models of SARS-CoV-2 infection ideally replicate, the essential development of mouse models for the study of Severe Acute Respiratory Syndrome and Middle Eastern Respiratory Syndrome and the basis of many of the models of COVID-19, and key clinical and pathologic features of currently available mouse models of SARS-CoV-2 infection.

Therapeutic efficacy of an oral nucleoside analog of remdesivir against SARS-CoV-2 pathogenesis in mice

The COVID-19 pandemic remains uncontrolled despite the rapid rollout of safe and effective SARS-CoV-2 vaccines, underscoring the need to develop highly effective antivirals. In the setting of waning immunity from infection and vaccination, breakthrough infections are becoming increasingly common and treatment options remain limited. Additionally, the emergence of SARS-CoV-2 variants of concern with their potential to escape therapeutic monoclonal antibodies emphasizes the need to develop second-generation oral antivirals targeting highly conserved viral proteins that can be rapidly deployed to outpatients. Here, we demonstrate the in vitro antiviral activity and in vivo therapeutic efficacy of GS-621763, an orally bioavailable prodrug of GS-441524, the parental nucleoside of remdesivir, which targets the highly conserved RNA-dependent RNA polymerase. GS-621763 exhibited significant antiviral activity in lung cell lines and two different human primary lung cell culture systems. The dose-proportional pharmacokinetic profile observed after oral administration of GS-621763 translated to dose-dependent antiviral activity in mice infected with SARS-CoV-2. Therapeutic GS-621763 significantly reduced viral load, lung pathology, and improved pulmonary function in COVID-19 mouse model. A direct comparison of GS-621763 with molnupiravir, an oral nucleoside analog antiviral currently in human clinical trial, proved both drugs to be similarly efficacious. These data demonstrate that therapy with oral prodrugs of remdesivir can significantly improve outcomes in SARS-CoV-2 infected mice. Thus, GS-621763 supports the exploration of GS-441524 oral prodrugs for the treatment of COVID-19 in humans.

Novel virus-like nanoparticle vaccine effectively protects animal model from SARS-CoV-2 infection

The key to battling the COVID-19 pandemic and its potential aftermath is to develop a variety of vaccines that are efficacious and safe, elicit lasting immunity, and cover a range of SARS-CoV-2 variants. Recombinant viral receptor-binding domains (RBDs) are safe vaccine candidates but often have limited efficacy due to the lack of virus-like immunogen display pattern. Here we have developed a novel virus-like nanoparticle (VLP) vaccine that displays 120 copies of SARS-CoV-2 RBD on its surface. This VLP-RBD vaccine mimics virus-based vaccines in immunogen display, which boosts its efficacy, while maintaining the safety of protein-based subunit vaccines. Compared to the RBD vaccine, the VLP-RBD vaccine induced five times more neutralizing antibodies in mice that efficiently blocked SARS-CoV-2 from attaching to its host receptor and potently neutralized the cell entry of variant SARS-CoV-2 strains, SARS-CoV-1, and SARS-CoV-1-related bat coronavirus. These neutralizing immune responses induced by the VLP-RBD vaccine did not wane during the two-month study period. Furthermore, the VLP-RBD vaccine effectively protected mice from SARS-CoV-2 challenge, dramatically reducing the development of clinical signs and pathological changes in immunized mice. The VLP-RBD vaccine provides one potentially effective solution to controlling the spread of SARS-CoV-2.

Cytotoxic Engineered Induced Neural Stem Cells as an Intravenous Therapy for Primary Non-Small Cell Lung Cancer and Triple-Negative Breast Cancer

Converting human fibroblasts into personalized induced neural stem cells (hiNSC) that actively seek out tumors and deliver cytotoxic agents is a promising approach for treating cancer. Herein, we provide the first evidence that intravenously-infused hiNSCs secreting cytotoxic agent home to and suppress the growth of non-small cell lung cancer (NSCLC) and triple-negative breast cancer (TNBC). Migration of hiNSCs to NSCLC and TNBC in vitro was investigated using time-lapse motion analysis, which showed directional movement of hiNSCs to both tumor cell lines. In vivo, migration of intravenous hiNSCs to orthotopic NSCLC or TNBC tumors was determined using bioluminescent imaging (BLI) and immunofluorescent post-mortem tissue analysis, which indicated that hiNSCs colocalized with tumors within 3 days of intravenous administration and persisted through 14 days. In vitro, efficacy of hiNSCs releasing cytotoxic TRAIL (hiNSC-TRAIL) was monitored using kinetic imaging of co-cultures, in which hiNSC-TRAIL therapy induced rapid killing of both NSCLC and TNBC. Efficacy was determined in vivo by infusing hiNSC-TRAIL or control cells intravenously into mice bearing orthotopic NSCLC or TNBC and tracking changes in tumor volume using BLI. Mice treated with intravenous hiNSC-TRAIL showed a 70% or 72% reduction in NSCLC or TNBC tumor volume compared with controls within 14 or 21 days, respectively. Safety was assessed by hematology, blood chemistry, and histology, and no significant changes in these safety parameters was observed through 28 days. These results indicate that intravenous hiNSCs-TRAIL seek out and kill NSCLC and TNBC tumors, suggesting a potential new strategy for treating aggressive peripheral cancers.

Chimeric spike mRNA vaccines protect against Sarbecovirus challenge in mice

The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003 and SARS-CoV-2 in 2019 highlights the need to develop universal vaccination strategies against the broader Sarbecovirus subgenus. Using chimeric spike designs, we demonstrate protection against challenge from SARS-CoV, SARS-CoV-2, SARS-CoV-2 B.1.351, bat CoV (Bt-CoV) RsSHC014, and a heterologous Bt-CoV WIV-1 in vulnerable aged mice. Chimeric spike messenger RNAs (mRNAs) induced high levels of broadly protective neutralizing antibodies against high-risk Sarbecoviruses. By contrast, SARS-CoV-2 mRNA vaccination not only showed a marked reduction in neutralizing titers against heterologous Sarbecoviruses, but SARS-CoV and WIV-1 challenge in mice resulted in breakthrough infections. Chimeric spike mRNA vaccines efficiently neutralized D614G, mink cluster five, and the UK B.1.1.7 and South African B.1.351 variants of concern. Thus, multiplexed-chimeric spikes can prevent SARS-like zoonotic coronavirus infections with pandemic potential.

Prevention and therapy of SARS-CoV-2 and the B.1.351 variant in mice

Improving clinical care for individuals infected with SARS-CoV-2 variants is a global health priority. Small-molecule antivirals like remdesivir (RDV) and biologics such as human monoclonal antibodies (mAbs) have demonstrated therapeutic efficacy against SARS-CoV-2, the causative agent of coronavirus disease 2019 (COVID-19). It is not known whether combination RDV/mAb will improve outcomes over single-agent therapies or whether antibody therapies will remain efficacious against variants. Here, we show that a combination of two mAbs in clinical trials, C144 and C135, have potent antiviral effects against even when initiated 48 h after infection and have therapeutic efficacy in vivo against the B.1.351 variant of concern (VOC). Combining RDV and antibodies provided a modest improvement in outcomes compared with single agents. These data support the continued use of RDV to treat SARS-CoV-2 infections and the continued clinical development of the C144 and C135 antibody combination to treat patients infected with SARS-CoV-2 variants.

In vivo assessment of pulmonary fibrosis and edema in rodents using the backscatter coefficient and envelope statistics

Quantitative ultrasound methods based on the backscatter coefficient (BSC) and envelope statistics have been used to quantify disease in a wide variety of tissues, such as prostate, lymph nodes, breast, and thyroid. However, to date, these methods have not been investigated in the lung. In this study, lung properties were quantified by BSC and envelope statistical parameters in normal, fibrotic, and edematous rat lungs in vivo. The average and standard deviation of each parameter were calculated for each lung as well as the evolution of each parameter with acoustic propagation time within the lung. The transport mean free path and backscattered frequency shift, two parameters that have been successfully used to assess pulmonary fibrosis and edema in prior work, were evaluated in combination with the BSC and envelope statistical parameters. Multiple BSC and envelope statistical parameters were found to provide contrast between control and diseased lungs. BSC and envelope statistical parameters were also significantly correlated with fibrosis severity using the modified Ashcroft fibrosis score as the histological gold standard. These results demonstrate the potential for BSC and envelope statistical parameters to improve the diagnosis of pulmonary fibrosis and edema as well as monitor pulmonary fibrosis.

Biodegradable polymeric solid implants for ultra-long-acting delivery of single or multiple antiretroviral drugs

Lack of adherence is a key barrier to a successful human immunodeficiency virus (HIV) treatment and prevention. We report on an ultra-long-acting (ULA) biodegradable polymeric solid implant (PSI) that can accommodate one or more antiretrovirals (e.g., dolutegravir (DTG) and rilpivirine (RPV)) at translatable human doses (65% wt.) in a single implant. PSIs are fabricated using a three-step process: (a) phase inversion of a drug/polymer solution to form an initial in-situ forming solid implant, (b) micronization of dried drug-loaded solid implants, and (c) compression of the micronized drug-loaded solid powder to generate the PSI. DTG and RPV can be pre-combined in a single PLGA-based solution to make dual-drug PSI; or formulated individually in PLGA-based solutions to generate separate micronized powders and form a bilayer dual-drug PSI. Results showed that in a single or bilayer dual-drug PSI, DTG and RPV exhibited physicochemical properties similar to their pure drug analogues. PSIs were well tolerated in vivo and effectively delivered drug(s) over 180 days with concentrations above 4× PA-IC90 after a single subcutaneous administration. While biodegradable and do not require removal, these PSIs can safely be removed to terminate the treatment if required. The versatility of this technology makes it attractive as an ULA drug delivery platform for HIV and various therapeutic applications.

Simulated Gastric Digestion and In Vivo Intestinal Uptake of Orally Administered CuO Nanoparticles and TiO2 E171 in Male and Female Rat Pups

Oral exposure to nanoparticles (NPs) during early life is an understudied area. The goals of this study were to evaluate the effect of pre-weaned rat gastric fluids on 50 nm CuO NPs and TiO2 E171 in vitro, and to evaluate uptake in vivo. The NP uptake was studied in vivo in male and female Sprague-Dawley rat pups following oral administration of four consecutive daily doses of 10 mg/kg CuO NPs, TiO2 E171, or vehicle control (water) between postnatal day (PND) 7-10. Rat pups were sacrificed on either PND10 or PND21. Simulated digestion led to dissolution of CuO NPs at the later ages tested (PND14 and PND21, but not PND7). In vivo intestinal uptake of CuO NPs and TiO2 E171 was observed by hyperspectral imaging of intestinal cross sections. Brightfield microscopy showed that the number of immune cells increased in the intestinal tissue following NP administration. Orally administered NPs led to low intestinal uptake of NPs and an increase in immune cells in the small and large intestine, suggesting that oral exposure to NPs during early life may lead to irritation or a low-grade inflammation. The long-term impact of increased immune cells in the intestinal tract during early life is unknown.

Common Mechanism of SARS-CoV and SARS-CoV-2 Pathogenesis across Species

Sarbecovirus (CoV) infections, including Severe Acute Respiratory CoV (SARS-CoV) and SARS-CoV-2, are considerable human threats. Human GWAS studies have recently identified loci associated with variation in SARS-CoV-2 susceptibility. However, genetically tractable models that reproduce human CoV disease outcomes are needed to mechanistically evaluate genetic determinants of CoV susceptibility. We used the Collaborative Cross (CC) and human GWAS datasets to elucidate host susceptibility loci that regulate CoV infections and to identify host quantitative trait loci that modulate severe CoV and pan-CoV disease outcomes including a major disease regulating loci including CCR9. CCR9 ablation resulted in enhanced titer, weight loss, respiratory dysfunction, mortality, and inflammation, providing mechanistic support in mitigating protection from severe SARS-CoV-2 pathogenesis across species. This study represents a comprehensive analysis of susceptibility loci for an entire genus of human pathogens conducted, identifies a large collection of susceptibility loci and candidate genes that regulate multiple aspects type-specific and cross-CoV pathogenesis, and also validates the paradigm of using the CC platform to identify common cross-species susceptibility loci and genes for newly emerging and pre-epidemic viruses.

Chimeric spike mRNA vaccines protect against Sarbecovirus challenge in mice

The emergence of SARS-CoV in 2003 and SARS-CoV-2 in 2019 highlights the need to develop universal vaccination strategies against the broader Sarbecovirus subgenus. Using chimeric spike designs, we demonstrate protection against challenge from SARS-CoV, SARS-CoV-2, SARS-CoV-2 B.1.351, bat CoV (Bt-CoV) RsSHC014, and a heterologous Bt-CoV WIV-1 in vulnerable aged mice. Chimeric spike mRNAs induced high levels of broadly protective neutralizing antibodies against high-risk Sarbecoviruses. In contrast, SARS-CoV-2 mRNA vaccination not only showed a marked reduction in neutralizing titers against heterologous Sarbecoviruses, but SARS-CoV and WIV-1 challenge in mice resulted in breakthrough infection. Chimeric spike mRNA vaccines efficiently neutralized D614G, UK B.1.1.7., mink cluster five, and the South African B.1.351 variant of concern. Thus, multiplexed-chimeric spikes can prevent SARS-like zoonotic coronavirus infections with pandemic potential.

A broadly neutralizing antibody protects against SARS-CoV, pre-emergent bat CoVs, and SARS-CoV-2 variants in mice

SARS-CoV in 2003, SARS-CoV-2 in 2019, and SARS-CoV-2 variants of concern (VOC) can cause deadly infections, underlining the importance of developing broadly effective countermeasures against Group 2B Sarbecoviruses, which could be key in the rapid prevention and mitigation of future zoonotic events. Here, we demonstrate the neutralization of SARS-CoV, bat CoVs WIV-1 and RsSHC014, and SARS-CoV-2 variants D614G, B.1.1.7, B.1.429, B1.351 by a receptor-binding domain (RBD)-specific antibody DH1047. Prophylactic and therapeutic treatment with DH1047 demonstrated protection against SARS-CoV, WIV-1, RsSHC014, and SARS-CoV-2 B1.351infection in mice. Binding and structural analysis showed high affinity binding of DH1047 to an epitope that is highly conserved among Sarbecoviruses. We conclude that DH1047 is a broadly neutralizing and protective antibody that can prevent infection and mitigate outbreaks caused by SARS-like strains and SARS-CoV-2 variants. Our results argue that the RBD conserved epitope bound by DH1047 is a rational target for pan Group 2B coronavirus vaccines.

Prevention and therapy of SARS-CoV-2 and the B.1.351 variant in mice

Improving the standard of clinical care for individuals infected with SARS-CoV-2 variants is a global health priority. Small molecule antivirals like remdesivir (RDV) and biologics such as human monoclonal antibodies (mAb) have demonstrated therapeutic efficacy against SARS-CoV-2, the causative agent of COVID-19. However, it is not known if combination RDV/mAb will improve outcomes over single agent therapies or whether antibody therapies will remain efficacious against variants. In kinetic studies in a mouse-adapted model of ancestral SARS-CoV-2 pathogenesis, we show that a combination of two mAbs in clinical trials, C144 and C135, have potent antiviral effects against even when initiated 48 hours after infection. The same antibody combination was also effective in prevention and therapy against the B.1.351 variant of concern (VOC). Combining RDV and antibodies provided a modest improvement in outcomes compared to single agents. These data support the continued use of RDV to treat SARS-CoV-2 infections and support the continued clinical development of the C144 and C135 antibody combination to treat patients infected with SARS-CoV-2 variants.

AIM2 in regulatory T cells restrains autoimmune diseases

The inflammasome initiates innate defense and inflammatory response by activating caspase-1 and pyroptotic cell death in myeloid cells^1,2. It is comprised of an innate immune receptor/sensor, pro-caspase-1, and a common adaptor molecule, ASC (apoptotic speck-containing protein with a CARD). Consistent with their pro-inflammatory function, caspase-1, ASC and NLRP3 exacerbate autoimmunity during experimental autoimmune encephalomyelitis (EAE) by enhancing IL-1β and IL-18 secretion in myeloid cells^3–6. Here we reveal an unexpected function of a DNA-binding inflammasome receptor, AIM2 (Absent in Melanoma 2)^7–10, in T regulatory cells (Tregs) to restrain two models of autoimmunity (experimental autoimmune encephalomyelitis and T cell-mediated colitis) by studying whole-body and Treg-specific Aim2^–/– mice. AIM2 is highly expressed by human and mouse Tregs, with its expression induced by TGF-β and its promoter occupied by transcription factors associated with Tregs, including Runx1, Ets1, Bcl11b and CREB. RNA-seq, biochemical and metabolic analyses revealed that AIM2 attenuates Akt-phosphorylation, mTOR, c-Myc and glycolysis, but promotes lipid oxidative phosphorylation in Tregs. Mechanistically, AIM2 interacts with the RACK1/PP2A-phosphatase complex to restrain Akt-phosphorylation. Lineage tracing demonstrates that AIM2 promotes the stability of Tregs during inflammation. While AIM2 is generally accepted as an inflammasome effector in myeloid cells, this report reveals a T cell-intrinsic role of AIM2 in restraining autoimmunity by diminishing Akt-mTOR signaling and altering immune-metabolism to enhance Treg stability.

Biodistribution, cardiac and neurobehavioral assessments, and neurotransmitter quantification in juvenile rats following oral administration of aluminum oxide nanoparticles

Little is known about the uptake, biodistribution, and biological responses of nanoparticles (NPs) and their toxicity in developing animals. Here, male and female juvenile Sprague-Dawley rats received four consecutive daily doses of 10 mg/kg Al₂ O₃ NP (diameter: 24 nm [transmission electron microscope], hydrodynamic diameter: 148 nm) or vehicle control (water) by gavage between postnatal days (PNDs) 17-20. Basic neurobehavioral and cardiac assessments were performed on PND 20. Animals were sacrificed on PND 21, and selected tissues were collected, weighed, and processed for histopathology or neurotransmitter analysis. The biodistribution of Al₂ O₃ NP in tissue sections of the intestine, liver, spleen, kidney, and lymph nodes were evaluated using enhanced dark-field microscopy (EDM) and hyperspectral imaging (HSI). Liver-to-body weight ratio was significantly increased for male pups administered Al₂ O₃ NP compared with control. HSI suggested that Al₂ O₃ NP was more abundant in the duodenum and ileum tissue of the female pups compared with the male pups, whereas the abundance of NP was similar for males and females in the other tissues. The abundance of NP was higher in the liver compared with spleen, lymph nodes, and kidney. Homovanillic acid and norepinephrine concentrations in brain were significantly decreased following Al₂ O₃ NP administration in female and male pups, whereas 5-hydroxyindoleacetic acid was significantly increased in male pups. EDM/HSI indicates intestinal uptake of Al₂ O₃ NP following oral administration. Al₂ O₃ NP altered neurotransmitter/metabolite concentrations in juvenile rats' brain tissues. Together, these data suggest that orally administered Al₂ O₃ NP interferes with the brain biochemistry in both female and male pups.