Proteomic and Single-Cell Transcriptomic Dissection of Human Plasmacytoid Dendritic Cell Response to Influenza Virus.

Plasmacytoid dendritic cells [pDCs] represent a rare innate immune subset uniquely endowed with the capacity to produce substantial amounts of type-I interferons. This function of pDCs is critical for effective antiviral defenses and has been implicated in autoimmunity. While IFN-I and select cytokines have been recognized as pDC secreted products, a comprehensive agnostic profiling of the pDC secretome in response to a physiologic stimulus has not been reported. We applied LC-MS/MS to catalogue the repertoire of proteins secreted by pDCs in the unperturbed condition and in response to challenge with influenza H1N1. We report the identification of a baseline pDC secretome, and the repertoire of virus-induced proteins including most type-I interferons, various cytokines, chemokines and granzyme B. Additionally, using single-cell RNA-seq [scRNA-seq], we perform multidimensional analyses of pDC transcriptional diversity immediately ex vivo and following stimulation. Our data evidence preexisting pDC heterogeneity, with subsequent highly specialized roles within the pDC population upon stimulation ranging from dedicated cytokine super-producers to cells with APC-like traits. Dynamic expression of transcription factors and surface markers characterize subclusters within activated pDCs. Integrating the proteomic and transcriptomic datasets confirms the pDC-subcluster origin of the proteins identified in the secretome. Our findings represent the most comprehensive molecular characterization of primary human pDCs at baseline, and in response to influenza virus, reported to date.

Investigations into SCAMP5, a candidate lupus risk gene expressed in plasmacytoid dendritic cells.

OBJECTIVE: We have investigated the molecular function of SCAMP5, a candidate risk gene for SLE exclusively expressed in plasmacytoid dendritic cells (pDCs) among peripheral leucocytes. METHODS: We tested the independence of the association in SCAMP5 with SLE by performing conditional analyses. We profiled the expression pattern of SCAMP5 among circulating leucocytes at the transcript and protein levels. Using lentiviral vectors, we localised the subcellular distribution of SCAMP5 alongside the interferon secretory pathway. We analysed pDCs for the expression of SCAMP5 and interferon production capacity by SCAMP5 genotype. Finally, we examined pDC-specific SCAMP5 isoforms by total RNAseq analysis and examined for genotype-associated quantitative differences therein. RESULTS: A conditional analysis revealed evidence of an independent genetic association of SCAMP5 with SLE. Among circulating leucocytes, SCAMP5 is uniquely expressed in pDCs at the transcript and protein levels, with main presence in the Golgi apparatus and minor presence at the cell periphery. In live cells, SCAMP5 displayed dynamic Golgi-cell surface trafficking and localised with the interferon secretory pathway. SCAMP5 did not differ in expression levels in pDCs between genotyped donors; however, a transient interferon secretory defect was noted in pDCs from donors carrying the risk genotype. CONCLUSIONS: SCAMP5 constitutes a novel SLE risk gene on the basis of genomic data and expression in a cell type widely implicated in SLE pathogenesis. While we could not find evidence of quantitative expression differences in SCAMP5 between genotyped donors, SCAMP5 remains an attractive gene to explore given its highly restricted expression pattern and colocalisation with interferon secretion.

Effectiveness of SARS-CoV-2 Decontamination and Containment in a COVID-19 ICU.

Background: Health care systems in the United States are continuously expanding and contracting spaces to treat patients with coronavirus disease 2019 (COVID-19) in intensive care units (ICUs). As a result, hospitals must effectively decontaminate and contain severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in constructed and deconstructed ICUs that care for patients with COVID-19. We assessed decontamination of a COVID-19 ICU and examined the containment efficacy of combined contact and droplet precautions in creating and maintaining a SARS-CoV-2-negative ICU "antechamber". Methods: To examine the efficacy of chemical decontamination, we used high-density, semi-quantitative environmental sampling to detect SARS-CoV-2 on surfaces in a COVID-19 ICU and COVID-19 ICU antechamber. Quantitative real-time polymerase chain reaction was used to measure viral RNA on surfaces. Viral location mapping revealed the distribution of viral RNA in the COVID-19 ICU and COVID-19 ICU antechamber. Results were further assessed using loop-mediated isothermal amplification. Results: We collected 224 surface samples pre-decontamination and 193 samples post-decontamination from a COVID-19 ICU and adjoining COVID-19 ICU antechamber. We found that 46% of antechamber objects were positive for SARS-CoV-2 pre-decontamination despite the construction of a swinging door barrier system, implementation of contact precautions, and installation of high-efficiency particulate air filters. The object positivity rate reduced to 32.1% and viral particle rate reduced by 95.4% following decontamination. Matched items had an average of 432.2 ± 2729 viral copies/cm2 pre-decontamination and 19.2 ± 118 viral copies/cm2 post-decontamination, demonstrating significantly reduced viral surface distribution (p < 0.0001). Conclusions: Environmental sampling is an effective method for evaluating decontamination protocols and validating measures used to contain SARS-CoV-2 viral particles. While chemical decontamination effectively removes detectable viral RNA from surfaces, our approach to droplet/contact containment with an antechamber was not highly effective. These data suggest that hospitals should plan for the potential of aerosolized virions when creating strategies to contain SARS-CoV-2.

Arg206Cys substitution in DNASE1L3 causes a defect in DNASE1L3 protein secretion that confers risk of systemic lupus erythematosus.

OBJECTIVES: To determine if the polymorphism encoding the Arg206Cys substitution in DNASE1L3 explains the association of the DNASE1L3/PXK gene locus with systemic lupus erythematosus (SLE) and to examine the effect of the Arg206Cys sequence change on DNASE1L3 protein function. METHODS: Conditional analysis for rs35677470 was performed on cases and controls with European ancestry from the SLE Immunochip study, and genotype and haplotype frequencies were compared. DNASE1L3 protein levels were measured in cells and supernatants of HEK293 cells and monocyte-derived dendritic cells expressing recombinant and endogenous 206Arg and 206Cys protein variants. RESULTS: Conditional analysis on rs35677470 eliminated the SLE risk association signal for lead single-nucleotide polymorphisms (SNPs) rs180977001 and rs73081554, which are found to tag the same risk haplotype as rs35677470. The modest effect sizes of the SLE risk genotypes (heterozygous risk OR=1.14 and homozygous risk allele OR=1.68) suggest some DNASE1L3 endonuclease enzyme function is retained. An SLE protective signal in PXK (lead SNP rs11130643) remained following conditioning on rs35677470. The DNASE1L3 206Cys risk variant maintained enzymatic activity, but secretion of the artificial and endogenous DNASE1L3 206Cys protein was substantially reduced. CONCLUSIONS: SLE risk association in the DNASE1L3 locus is dependent on the missense SNP rs35677470, which confers a reduction in DNASE1L3 protein secretion but does not eliminate its DNase enzyme function.

Evidence supporting the use of peptides and peptidomimetics as potential SARS-CoV-2 (COVID-19) therapeutics.

During a disease outbreak/pandemic situation such as COVID-19, researchers are in a prime position to identify and develop peptide-based therapies, which could be more rapidly and cost-effectively advanced into a clinical setting. One drawback of natural peptide drugs, however, is their proteolytic instability; peptidomimetics can help to overcome this caveat. In this review, we summarize peptide and peptide-based therapeutics that target one main entry pathway of SARS-CoV-2, which involves the host ACE2 receptor and viral spike (S) protein interaction. Furthermore, we discuss the advantages of peptidomimetics and other potential targets that have been studied using peptide-based therapeutics for COVID-19.

Bispecific chimeric antigen receptors targeting the CD4 binding site and high-mannose Glycans of gp120 optimized for anti-human immunodeficiency virus potency and breadth with minimal immunogenicity.

BACKGROUND AIMS: Chimeric antigen receptors (CARs) offer great potential toward a functional cure of human immunodeficiency virus (HIV) infection. To achieve the necessary long-term virus suppression, we believe that CARs must be designed for optimal potency and anti-HIV specificity, and also for minimal probability of virus escape and CAR immunogenicity. CARs containing antibody-based motifs are problematic in the latter regard due to epitope mutation and anti-idiotypic immune responses against the variable regions. METHODS: We designed bispecific CARs, each containing a segment of human CD4 linked to the carbohydrate recognition domain of a human C-type lectin. These CARs target two independent regions on HIV-1 gp120 that presumably must be conserved on clinically significant virus variants (i.e., the primary receptor binding site and the dense oligomannose patch). Functionality and specificity of these bispecific CARs were analyzed in assays of CAR-T cell activation and spreading HIV-1 suppression. RESULTS: T cells expressing a CD4-dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DCSIGN) CAR displayed robust stimulation upon encounter with Env-expressing targets, but negligible activity against intercellular adhesion molecule (ICAM)-2 and ICAM-3, the natural dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin ligands. Moreover, the presence of the lectin moiety prevented the CD4 from acting as an entry receptor on CCR5-expressing cells, including CD8+ T cells. However, in HIV suppression assays, the CD4-DCSIGN CAR and the related CD4-liver/lymph node-specific intercellular adhesion molecule-3-grabbing non-integrin CAR displayed only minimally increased potency compared with the CD4 CAR against some HIV-1 isolates and reduced potency against others. By contrast, the CD4-langerin and CD4-mannose binding lectin (MBL) CARs uniformly displayed enhanced potency compared with the CD4 CAR against all the genetically diverse HIV-1 isolates examined. Further experimental data, coupled with known biological features, suggest particular advantages of the CD4-MBL CAR. DISCUSSION: These studies highlight features of bispecific CD4-lectin CARs that achieve potency enhancement by targeting two distinct highly conserved Env determinants while lacking immunogenicity-prone antibody-based motifs.

Novel CD4-Based Bispecific Chimeric Antigen Receptor Designed for Enhanced Anti-HIV Potency and Absence of HIV Entry Receptor Activity.

UNLABELLED: Adoptive transfer of CD8 T cells genetically engineered to express "chimeric antigen receptors" (CARs) represents a potential approach toward an HIV infection "functional cure" whereby durable virologic suppression is sustained after discontinuation of antiretroviral therapy. We describe a novel bispecific CAR in which a CD4 segment is linked to a single-chain variable fragment of the 17b human monoclonal antibody recognizing a highly conserved CD4-induced epitope on gp120 involved in coreceptor binding. We compared a standard CD4 CAR with CD4-17b CARs where the polypeptide linker between the CD4 and 17b moieties is sufficiently long (CD4-35-17b CAR) versus too short (CD4-10-17b) to permit simultaneous binding of the two moieties to a single gp120 subunit. When transduced into a peripheral blood mononuclear cell (PBMC) or T cells thereof, all three CD4-based CARs displayed specific functional activities against HIV-1 Env-expressing target cells, including stimulation of gamma interferon (IFN-γ) release, specific target cell killing, and suppression of HIV-1 pseudovirus production. In assays of spreading infection of PBMCs with genetically diverse HIV-1 primary isolates, the CD4-10-17b CAR displayed enhanced potency compared to the CD4 CAR whereas the CD4-35-17b CAR displayed diminished potency. Importantly, both CD4-17b CARs were devoid of a major undesired activity observed with the CD4 CAR, namely, rendering the transduced CD8(+) T cells susceptible to HIV-1 infection. Likely mechanisms for the superior potency of the CD4-10-17b CAR over the CD4-35-17b CAR include the greater potential of the former to engage in the serial antigen binding required for efficient T cell activation and the ability of two CD4-10-17b molecules to simultaneously bind a single gp120 subunit. IMPORTANCE: HIV research has been energized by prospects for a cure for HIV infection or, at least, for a "functional cure" whereby antiretroviral therapy can be discontinued without virus rebound. This report describes a novel CD4-based "chimeric antigen receptor" (CAR) which, when genetically engineered into T cells, gives them the capability to selectively respond to and kill HIV-infected cells. This CAR displays enhanced features compared to previously described CD4-based CARs, namely, increased potency and avoidance of the undesired rendering of the genetically modified CD8 T cells susceptible to HIV infection. When adoptively transferred back to the individual, the genetically modified T cells will hopefully provide durable killing of infected cells and sustained virus suppression without continued antiretroviral therapy, i.e., a functional cure.

Altering murine leukemia virus integration through disruption of the integrase and BET protein family interaction.

We report alterations to the murine leukemia virus (MLV) integrase (IN) protein that successfully result in decreasing its integration frequency at transcription start sites and CpG islands, thereby reducing the potential for insertional activation. The host bromo and extraterminal (BET) proteins Brd2, 3 and 4 interact with the MLV IN protein primarily through the BET protein ET domain. Using solution NMR, protein interaction studies, and next generation sequencing, we show that the C-terminal tail peptide region of MLV IN is important for the interaction with BET proteins and that disruption of this interaction through truncation mutations affects the global targeting profile of MLV vectors. The use of the unstructured tails of gammaretroviral INs to direct association with complexes at active promoters parallels that used by histones and RNA polymerase II. Viruses bearing MLV IN C-terminal truncations can provide new avenues to improve the safety profile of gammaretroviral vectors for human gene therapy.