Probes for INS

Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the susceptibility of animals and their potential to act as reservoirs or intermediate hosts for the virus has been of significant interest. Pigs are susceptible to multiple coronaviruses and have been used as an animal model for other human infectious diseases. Research groups have experimentally challenged swine with human SARS-CoV-2 isolates with results suggesting limited to no viral replication. For this study, a SARS-CoV-2 isolate obtained from a tiger which is identical to human SARS-CoV-2 isolates detected in New York City and contains the D614G S mutation was utilized for inoculation. Pigs were challenged via intravenous, intratracheal, or intranasal routes of inoculation (n = 4/route). No pigs developed clinical signs, but at least one pig in each group had one or more PCR positive nasal/oral swabs or rectal swabs after inoculation. All pigs in the intravenous group developed a transient neutralizing antibody titer, but only three other challenged pigs developed titers greater than 1:8. No gross or histologic changes were observed in tissue samples collected at necropsy. In addition, no PCR positive samples were positive by virus isolation. Inoculated animals were unable to transmit virus to naïve contact animals. The data from this experiment as well as from other laboratories supports that swine are not likely to play a role in the epidemiology and spread of SARS-CoV-2.

The severe acute respiratory distress syndrome-associated coronavirus-2 (SARS-CoV-2), the etiologic agent of Coronavirus disease 2019 (COVID-19), is a single-stranded RNA virus whose sequence is known. COVID-19 is associated with a heterogeneous clinical phenotype ranging from asymptomatic to fatal disease. It appears that access to nasopharyngeal respiratory epithelia expressing angiotensin-converting enzyme (ACE) 2, the receptor for SARS CoV-2, is followed by viral replication in the pulmonary alveolar septal capillary bed. We have shown in prior studies that incomplete viral particles, termed pseudovirions, dock to deep subcutaneous and other vascular beds potentially contributing to the prothrombotic state and systemic complement activation that characterizes severe and critical COVID-19. A variety of skin rashes have been described in the setting of SARS-CoV-2 infection and more recently, following COVID-19 vaccination. The vaccines deliver a laboratory synthesized mRNA that encodes a protein that is identical to the spike glycoprotein of SARS-COV-2 allowing the production of immunogenic spike glycoprotein that will then elicit T cell and B cell adaptive immune responses. In this paper we review an array of cutaneous manifestations of COVID-19 that provide an opportunity to study critical pathophysiologic mechanisms that underlie all clinical facets of COVID-19 ranging from asymptomatic/mild to severe and critical COVID-19. We classify cutaneous COVID-19 according to underlying pathophysiologic principles. In this regard we propose two main pathways: 1) complement mediated thrombotic vascular injury syndromes deploying the alternative and mannan binding lectin pathways in the setting of severe and critical COVID-19 and 2) the robust T cell and type I interferon driven inflammatory and humoral driven immune complex mediated vasculitic cutaneous reactions seen with mild and moderate COVID-19. Novel data on cutaneous vaccine reactions are presented that manifest a clinical and morphologic parallel with similar eruptions seen in patients suffering from mild and moderate COVID-19 and in most cases represent systemic eczematoid hypersensitivity reactions to a putative vaccine based antigen. Finally, we show for the first time the localization of human synthesized spike glycoprotein following the COVID-19 vaccine to the cutaneous and subcutaneous vasculature confirming the ability of SARS CoV-2 spike glycoprotein to bind endothelium in the absence of intact virus.

Abstract Background A parallel downregulation of brain-derived neurotrophic factor (BDNF) and somatostatin (SST), a marker of inhibitory γ-amino-butyric acid (GABA) interneurons which target pyramidal cell dendrites, has been reported in several brain areas of subjects with major depressive disorder (MDD), and rodent genetic studies suggests they are linked and both contribute to the illness. However, the mechanism by which they contribute to the pathophysiology of the illness has remained elusive. Methods With qPCR, we determined the expression level of BDNF transcript variants and synaptic markers in the prefrontal cortex (PFC) of MDD patients and matched controls (n=19/group) and of C57BL/6J mice exposed to chronic stress or control conditions (n=12/group). We next suppressed BDNF transcripts with long 3’ untranslated region (L-3’-UTR) using small hairpin RNA (shRNA) and investigated changes in cell morphology, gene expression and behavior. Results L-3’-UTR containing BDNF mRNAs, which migrate to distal dendrites of pyramidal neurons, are selectively reduced and highly correlated with SST expression in the PFC of MDD subjects. A similar downregulation occurs in mice submitted to chronic stress. We next show that Bdnf L-3’-UTR knockdown is sufficient to induce (i) dendritic shrinkage in cortical neurons, (ii) cell-specific MDD-like gene changes (including Sst downregulation), and (iii) depressive-/anxiety-like behaviors. The translational validity of the Bdnf L-3’-UTR shRNA-treated mice was confirmed by significant cross-species correlation of changes in MDD-associated gene expression. Conclusions These findings provide evidence for a novel MDD-related pathological mechanism linking local neurotrophic support, pyramidal cell structure, dendritic inhibition and mood regulation.

Ophthalmic manifestations and tissue tropism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported in association with coronavirus disease 2019 (COVID-19), but the pathology and cellular localization of SARS-CoV-2 are not well characterized. The objective of this study was to evaluate macroscopic and microscopic changes and investigate cellular localization of SARS-CoV-2 across ocular tissues at autopsy. Ocular tissues were obtained from 25 patients with COVID-19 at autopsy. SARS-CoV-2 nucleocapsid gene RNA was previously quantified by droplet digital PCR from one eye. For this current study, contralateral eyes from 21 patients were fixed in formalin and subject to histopathologic examination. From the other four patients, sections of the droplet digital PCR-positive eyes were evaluated by in situ hybridization to determine the cellular localization of SARS-CoV-2 spike gene RNA. Histopathologic abnormalities, including cytoid bodies, vascular changes, and retinal edema, with minimal or no inflammation in ocular tissues were observed in all 21 cases evaluated. In situ hybridization localized SARS-CoV-2 RNA to neuronal cells of the retinal inner and outer layers, ganglion cells, corneal epithelia, scleral fibroblasts, and oligodendrocytes of the optic nerve. In conclusion, within ocular tissues, a range of common histopathologic alterations were identified, and SARS-CoV-2 RNA was localized to multiple cell types. Further studies will be required to determine whether the alterations observed were caused by SARS-CoV-2 infection, the host immune response, and/or preexisting comorbidities.

The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV-2) and its expansion to a worldwide pandemic resulted in efforts to assess and develop interventions to reduce the disease burden. Despite the introduction of vaccine programmes against SARS-CoV-2, global incidence levels in early 2022 remained high, demonstrating a need for the development of physiologically relevant models, which are essential for the identification of alternative antiviral strategies. The hamster model of SARS-CoV-2 infection has been widely adopted due to similarities with humans in terms of host cell entry mechanism (via ACE2), and aspects of symptomology and virus shedding. We have previously described a natural transmission hamster model that better represents the natural course of infection. In the present study, we have conducted further testing of the model using the first-in-class antiviral Neumifil, which has previously shown promise against SARS-CoV-2 after a direct intranasal challenge. Neumifil is an intranasally delivered carbohydrate-binding module (CBM) which reduces the binding of viruses to their cellular receptor. By targeting the host cell, Neumifil has the potential to provide broad protection against multiple pathogens and variants. This study demonstrates that using a combination of a prophylactic and therapeutic delivery of Neumifil significantly reduces the severity of clinical signs in animals infected via a natural route of transmission and indicates a reduction of viral loads in the upper respiratory tract. Further refinements of the model are required in order to ensure the adequate transmission of the virus. However, our results provide additional data to the evidence base of Neumifil efficacy against respiratory virus infection and demonstrate that the transmission model is a potentially valuable tool for testing antiviral compounds against SARS-CoV-2.

Current public health initiatives to contain the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) global pandemic focus on expanding vaccination efforts to include vulnerable populations such as pregnant people. Vaccines using messenger ribonucleic acid (mRNA) technology rely on translation by immune cells, primarily at the injection site. Hesitancy remains among the general population regarding the safety of mRNA vaccines during gestation, and it remains unknown whether the SARS-CoV-2 Spike protein (the product of mRNA vaccines available) accumulates in the placenta after vaccination. Objective: To determine whether Spike protein translation and accumulation occurs in placental tissue in the context of recent mRNA SARC-CoV-2 vaccination during pregnancy. We identified 48 patients receiving one or two doses of mRNA SARS-CoV-2 vaccine during gestation and used immunohistochemistry against SARS-CoV-2 Spike protein in formalin-fixed, paraffin-embedded placental tissue. One placenta, positive for SARS-CoV-2 RNA by in situ hybridization (ISH) was used as positive control. Seven term placentas collected prior to the emergence of SARS-CoV-2 served as negative controls. Eighty one percent of patients in the study group underwent third-trimester delivery; remaining had a first-trimester spontaneous abortion or elective second-trimester termination. Patients received two (52%) or one (48%) vaccine doses during pregnancy, with a median interval between latest dose and delivery of 13 days (range 2-79 days). Most (63%) cases had their latest dose within 15 days prior to delivery. All the placentas in the study and negative control groups were negative for SARS-CoV-2 immunohistochemistry. Six study cases with short vaccine-delivery intervals (2-7 days) were subjected to SARS-CoV-2 ISH and were negative. Our findings suggest that mRNA vaccines do not reach significant concentrations in the placenta given the absence of definitive SARS-CoV-2 Spike protein accumulation in placental tissue. This observation provides evidence supporting the safety of mRNA vaccines to the placental-fetal unit.

The local and long-range connectivity of cortical neurons are considered instrumental to the functional repertoire of the cortical region in which they reside. In cortical networks, distinct cell types build local circuit structures enabling computational operations. Computations in the medial prefrontal cortex (mPFC) are thought to be central to cognitive operation, including decision-making and memory. We used a retrograde trans-synaptic rabies virus system to generate brain-wide maps of the input to excitatory neurons as well as three inhibitory interneuron subtypes in the mPFC. On the global scale the input patterns were found to be mainly cell type independent, with quantitative differences in key brain regions, including the basal forebrain. Mapping of the local mPFC network revealed high connectivity between the different subtypes of interneurons. The connectivity mapping gives insight into the information that the mPFC processes and the structural architecture underlying the mPFC's unique functions.

Clinical evidence of vascular dysfunction and hypercoagulability as well as pulmonary vascular damage and microthrombosis are frequently reported in severe cases of human coronavirus disease 2019 (COVID-19). Syrian golden hamsters recapitulate histopathologic pulmonary vascular lesions reported in patients with COVID-19. Here, special staining techniques and transmission electron microscopy further define vascular pathologies in a Syrian golden hamster model of human COVID-19. The results show that regions of active pulmonary inflammation in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are characterized by ultrastructural evidence of endothelial damage with platelet marginalization and both perivascular and subendothelial macrophage infiltration. SARS-CoV-2 antigen/RNA was not detectable within affected blood vessels. Taken together, these findings suggest that the prominent microscopic vascular lesions in SARS-CoV-2-inoculated hamsters are likely due to endothelial damage followed by platelet and macrophage infiltration.

Despite universal recommendations for COVID-19 mRNA vaccination in pregnancy, uptake has been lower than desired. There have been limited studies of the direct impact of COVID-19 mRNA vaccine exposure in human placental tissue. Using a primary human villous explant model, we investigated the uptake of two common mRNA vaccines (BNT162b2 Pfizer-BioNTech or mRNA-1273 Moderna), and whether exposure altered villous cytokine responses. Explants derived from second or third trimester chorionic villi were incubated with vaccines at supraphysiologic concentrations and analyzed at two time points. We observed minimal uptake of mRNA vaccines in placental explants by in situ hybridization and quantitative RT-PCR. No specific or global cytokine response was elicited by either of the mRNA vaccines in multiplexed immunoassays. Our results suggest that the human placenta does not readily absorb the COVID-19 mRNA vaccines nor generate a significant inflammatory response after exposure.

The ghrelin producing ε-cell represents the fifth endocrine cell type in human pancreatic islets. The abundance of ε-cells in adult pancreas is extremely low, which has hampered the investigation on the molecular pathways regulating the development and the function of this cell type. In this study, we explored the molecular features defining the function of pancreatic ε-cells isolated from adult non-diabetic donors using single-cell RNA sequencing technology. We focus on transcription factors, cell surface receptors and genes involved in metabolic pathways that contribute to regulation of cellular function. Furthermore, the genes that separate ε-cells from the other islet endocrine cell types are presented. This study expands prior knowledge about the genes important for the function of the ε-cell during development and provides a resource to interrogate the transcriptome of this rare human islet cell type.