Platform for the interdisciplinary study of cardiovascular, metabolic and neurovascular diseases (PICMAN) protocol

Through extensive multisystem phenotyping, the central aim of Project PICMAN is to correlate metabolic flexibility to measures of cardiometabolic health, including myocardial diastolic dysfunction, coronary and cerebral atherosclerosis, body fat distribution and severity of non-alcoholic fatty liver disease. This cohort will form the basis of larger interventional trials targeting metabolic inflexibility in the prevention of cardiovascular disease. Participants aged 21-72 years with no prior manifest atherosclerotic cardiovascular disease (ASCVD) are being recruited from a preventive cardiology clinic and an existing cohort of non-alcoholic fatty liver disease (NAFLD) in an academic medical centre. A total of 120 patients will be recruited in the pilot phase of this study and followed up for 5 years. Those with 10-year ASCVD risk ≥ 5% as per the QRISK3 calculator are eligible. Those with established diabetes mellitus are excluded. Participants recruited undergo a detailed assessment of health behaviours and physical measurements. Participants also undergo a series of multimodality clinical phenotyping comprising cardiac tests, vascular assessments, metabolic tests, liver and neurovascular testing. Blood samples are also being collected and banked for plasma biomarkers, 'multi-omics analyses' and for generation of induced pluripotent stem cells (iPSC). Extensive evidence points to metabolic dysregulation as an early precursor of cardiovascular disease, particularly in Asia. We hypothesise that quantifiable metabolic inflexibility may be representative of an individual in his/her silent, but high-risk progression towards insulin resistance, diabetes and cardiovascular disease. The platform for interdisciplinary cardiovascular-metabolic-neurovascular diseases (PICMAN) is a pilot, prospective, multi-ethnic cohort study.

SHEAR saliva collection device augments sample properties for improved analytical performance

Despite being a convenient clinical substrate for biomonitoring, saliva's widespread utilization has not yet been realized. The non-Newtonian, heterogenous, and highly viscous nature of saliva complicate the development of automated fluid handling processes that are vital for accurate diagnoses. Furthermore, conventional saliva processing methods are resource and/or time intensive precluding certain testing capabilities, with these challenges aggravated during a pandemic. The conventional approaches may also alter analyte structure, reducing application opportunities in point-of-care diagnostics. To overcome these challenges, we introduce the SHEAR saliva collection device that mechanically processes saliva, in a rapid and resource-efficient way. We demonstrate the device's impact on reducing saliva's viscosity, improving sample's uniformity, and increasing diagnostic performance of a COVID-19 rapid antigen test. Additionally, a formal user experience study revealed generally positive comments. SHEAR saliva collection device may support realization of the saliva's potential, particularly in large-scale and/or resource-limited settings for global and community diagnostics.

SARS-CoV-2 spike protein as a bacterial lipopolysaccharide delivery system in an overzealous inflammatory cascade

Accumulating evidence indicates a potential role for bacterial lipopolysaccharide (LPS) in the overactivation of the immune response during SARS-CoV-2 infection. LPS is recognized by Toll-like receptor 4, mediating proinflammatory effects. We previously reported that LPS directly interacts with SARS-CoV-2 spike (S) protein and enhances proinflammatory activities. Using native gel electrophoresis and hydrogen-deuterium exchange mass spectrometry, we showed that LPS binds to multiple hydrophobic pockets spanning both the S1 and S2 subunits of the S protein. Molecular simulations validated by a microscale thermophoresis binding assay revealed that LPS binds to the S2 pocket with a lower affinity compared to S1, suggesting a role as an intermediate in LPS transfer. Congruently, nuclear factor-kappa B (NF-κB) activation in monocytic THP-1 cells is strongly boosted by S2. Using NF-κB reporter mice followed by bioimaging, a boosting effect was observed for both S1 and S2, with the former potentially facilitated by proteolysis. The Omicron S variant binds to LPS, but with reduced affinity and LPS boosting in vitro and in vivo. Taken together, the data provide a molecular mechanism by which S protein augments LPS-mediated hyperinflammation.

Uncovering cryptic pockets in the SARS-CoV-2 spike glycoprotein

The COVID-19 pandemic has prompted a rapid response in vaccine and drug development. Herein, we modeled a complete membrane-embedded SARS-CoV-2 spike glycoprotein and used molecular dynamics simulations with benzene probes designed to enhance discovery of cryptic pockets. This approach recapitulated lipid and host metabolite binding sites previously characterized by cryo-electron microscopy, revealing likely ligand entry routes, and uncovered a novel cryptic pocket with promising druggable properties located underneath the 617-628 loop. A full representation of glycan moieties was essential to accurately describe pocket dynamics. A multi-conformational behavior of the 617-628 loop in simulations was validated using hydrogen-deuterium exchange mass spectrometry experiments, supportive of opening and closing dynamics. The pocket is the site of multiple mutations associated with increased transmissibility found in SARS-CoV-2 variants of concern including Omicron. Collectively, this work highlights the utility of the benzene mapping approach in uncovering potential druggable sites on the surface of SARS-CoV-2 targets.

Abstract 1425: Chimeric antigen receptors based on T cell receptor-like antibodies

T cells are essential in adaptive immunity and play an indispensable role to eliminate abnormal or virus infected cells. By merging antibody technology and cell engineering, T cells equipped with a chimeric antigen receptor (CAR) can be redirected to the target in a non-MHC restricted fashion. Within the past few years, clinical trials using CAR T cells engineered to recognize B cell cancers have shown high rates of response (70%-90%) and durability of response that are unprecedented in acute and chronic leukaemia. However, severe toxicity has been observed due to massive, and to some extent nonspecific, T cell activation. Although CARs have been improved and investigated heavily, the extent to which a CAR is similar to its parental TCR extra- or intracellularly, and whether critical elements involved in normal TCR signalling are kept or rewired in CAR signalling, are unclear. A better understanding of these questions would greatly facilitate improvements in CAR technology and its usefulness in clinical practice. A CAR targeting a peptide-MHC complex (using an Fv from an antibody that recognizes MHC-peptide: in other words, a TCR-like Ab) mimics the process of TCR recognition and takes advantage of CAR technologies developed so far. It is thus an excellent study object to compare TCR and CAR signalling. Well-built research methods on TCR can be transferred immediately to TCR-like CAR, while the knowledge and findings generated through the studies of TCR-like CAR can in turn renew our perceptions on TCR.

TCR-like antibodies targeting the EBV epitopes LMP1125-133, LMP2A426-434 or EBNA1562-570, were engineered as CARs. We find that conformation change, if any, upon ligand binding is not enough to activate downstream TCR signalling, but oligomerization is a crucial factor. Although CAR with a TCR-like specificity can recruit CD8 co-receptor to the immunological synapse, it is dispensable for activation of the T cell. Furthermore, the activation kinetics of CAR and TCR are distinctly different. TCR shows a pulse-like activation, whereas CAR shows an activation that gradually plateaus and remains steady. These unique properties of CAR identified in our study demonstrate that CAR signalling properties may be amenable to modifications leading to better specificity and activity in vivo. Our long-term goal is that the TCR-like CAR can be used to combat EBV induced Nasopharyngeal Carcinoma.

Citation Format: Ling Wu, Joanna Brzostek, Shvetha Sankaran, Triscilla Tan, Conrad Chan, Jiawei Yap, Junyun Lai, Paul MacAry, Nicholas Gascoigne. Chimeric antigen receptors based on T cell receptor-like antibodies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1425.

A potent neutralizing antibody with therapeutic potential against all four serotypes of dengue virus

A therapy for dengue is still elusive. We describe the neutralizing and protective capacity of a dengue serotype-cross-reactive antibody isolated from the plasmablasts of a patient. Antibody SIgN-3C neutralized all four dengue virus serotypes at nano to picomolar concentrations and significantly decreased viremia of all serotypes in adult mice when given 2 days after infection. Moreover, mice were protected from pathology and death from a lethal dengue virus-2 infection. To avoid potential Fc-mediated uptake of immune complexes and ensuing enhanced infection, we introduced a LALA mutation in the Fc part. SIgN-3C-LALA was as efficient as the non-modified antibody in neutralizing dengue virus and in protecting mice while antibody-dependent enhancement was completely abrogated. The epitope of the antibody includes conserved amino acids in all three domains of the glycoprotein, which can explain its cross-reactivity. SIgN-3C-LALA neutralizes dengue virus both pre and post-attachment to host cells. These attributes likely contribute to the remarkable protective capacity of SIgN-3C.

Leucocyte subset-specific type 1 interferon signatures in SLE and other immune-mediated diseases

Objectives

Type 1 interferons (IFN-1) are implicated in the pathogenesis of systemic lupus erythematosus (SLE), but most studies have only reported the effect of IFN-1 on mixed cell populations. We aimed to define modules of IFN-1-associated genes in purified leucocyte populations and use these as a basis for a detailed comparative analysis.

Methods

CD4+ and CD8+ T cells, monocytes and neutrophils were purified from patients with SLE, other immune-mediated diseases and healthy volunteers and gene expression then determined by microarray. Modules of IFN-1-associated genes were defined using weighted gene coexpression network analysis. The composition and expression of these modules was analysed.

Results

1150 of 1288 IFN-1-associated genes were specific to myeloid subsets, compared with 11 genes unique to T cells. IFN-1 genes were more highly expressed in myeloid subsets compared with T cells. A subset of neutrophil samples from healthy volunteers (HV) and conditions not classically associated with IFN-1 signatures displayed increased IFN-1 gene expression, whereas upregulation of IFN-1-associated genes in T cells was restricted to SLE.

Conclusions

Given the broad upregulation of IFN-1 genes in neutrophils including in some HV, investigators reporting IFN-1 signatures on the basis of whole blood samples should be cautious about interpreting this as evidence of bona fide IFN-1-mediated pathology. Instead, specific upregulation of IFN-1-associated genes in T cells may be a useful biomarker and a further mechanism by which elevated IFN-1 contributes to autoimmunity in SLE.

Human CD8 T cells drive Th1 responses through differentiation of TNF/iNOS-producing dendritic cells (147.4)

TNF/iNOS-producing (Tip) dendritic cells have been shown to arise during inflammation and are important mediators of immune defense. However, it is still relatively unclear which cell types contribute to their differentiation. Here we show that CD8 T-cells, through the interaction with DCs, can induce the rapid development of human monocytes into Tip-DCs which express high levels of TNF-α and iNOS. These cells exhibited T-cell priming ability, expressed high levels of MHC class II, up-regulated co-stimulatory molecules CD40, CD80, CD86, toll-like receptors TLR2, TLR3, TLR4, chemokine receptors CCR1 and CX3CR1 and expressed the classical mature DC marker, CD83. Differentiation of monocytes into Tip-DCs was partially dependent on IFN-γ as blocking the IFN-γ receptor on monocytes resulted in a significant decrease in CD40, CD83 expression and TNF-α production. Importantly, these Tip-DCs were capable of further driving Th1 responses by priming naive CD4 T-cells for proliferation and IFN-γ production and this was partially dependent on Tip-DC’s production of TNF-α and NO. Our study hence identifies a role for CD8 T-cells in orchestrating Th1-mediating signals through the differentiation of monocytes into Th1-inducing Tip-DCs.

Anti-lipid response in Systemic Lupus Erythematosus (44.4)

Systemic Lupus Erythematosus (SLE) is a chronic, multisystem, autoimmune disorder with a broad range of clinical presentations. One of the main factors, proposed to contribute to the development of clinical manifestations of SLE is accumulation and impaired clearance of immune complexes. The aim of the present study was to investigate lipid and anti-lipid antibody profiles in SLE patients’ plasma using ELISA and gas chromatography-mass spectrometry (GC-MS). The SLE cohort employed in this study is composed of 24 subjects and disease monitoring was undertaken with serial BILAG disease scoring. The blood was collected at three time points: at the moment of flare; and 3-months/12-months after treatment had started. For oxysterols (7α-hydroxycholesterol, 7β-hydroxycholesterol, 7-ketocholesterol) we report a trend where lipid levels and corresponding anti-lipid IgG concentrations are significantly reduced during the course of treatment. For phospholipids (oxidized phosphatidylcholine, cardiolipin) we also show high levels of anti-lipid IgG during flare or active disease. Using GC-MS and ELISA we have confirmed an association of high lipid levels and high anti-lipid IgG level with disease flare in comparison to 12 months after the commencement of treatment. We propose that auto anti-lipid IgGs should now be considered a component of the accumulated immune complexes in SLE and thus may contribute to disease pathogenesis.

CD40 is a cellular receptor mediating mycobacterial heat shock protein 70 stimulation of CC-chemokines

The 70 kDa mycobacterial heat shock protein (Mtb HSP70) stimulates mononuclear cells to release CC-chemokines. We now show that this function of Mtb HSP70, but not human HSP70, is dependent on the cell surface expression of CD40. Deletion of the CD40 cytoplasmic tail abolished, and CD40 antibody inhibited, Mtb HSP70 stimulation of CC-chemokine release. Mtb HSP70 stimulated THP1, KG1 cells, and monocyte-derived dendritic cells to produce RANTES. Specific binding of CD40-transfected HEK 293 cells to Mtb HSP70 was demonstrated by surface plasmon resonance. Coimmunoprecipitation of Mtb HSP70 with CD40 indicates a physical association between these molecules. The results suggest that CD40 is critical in microbial HSP70 binding and stimulation of RANTES production.