Selected Grantee Publications
A Symphony of Destruction: Dynamic Differential Fibrinogenolytic Toxicity by Rattlesnake (Crotalus and Sistrurus) Venoms
Seneci et al., Comparative Biochemistry and Physiology Part C. 2021.
https://pubmed.ncbi.nlm.nih.gov/33766656/
This study adopts rattlesnakes as a model group to investigate the evolutionary history of venom coagulotoxicity in the context of phylogenetics, natural history, and biology. Venom-induced clotting of human plasma and fibrinogen was determined and mapped onto the rattlesnake phylogenetic tree to reconstruct the evolution of coagulotoxicity across the group. Results indicate that venom phenotype is often independent of phylogenetic relationships in rattlesnakes, suggesting the importance of diet and/or other environmental variables. This study is the most comprehensive effort to date to characterize the evolutionary and biological aspects of coagulotoxins in rattlesnake venom. Further research at finer taxonomic levels is recommended. Supported by ORIP (P40OD010960).
Phase Separation Drives Aberrant Chromatin Looping and Cancer Development
Ahn et al., Nature. 2021.
https://doi.org/10.1038/s41586-021-03662-5
How unstructured intrinsically disordered regions (IDRs) contribute to oncogenesis is elusive. Using an Orbitrap fusion tribrid mass spectrometer, investigators show that IDRs contained within NUP98–HOXA9, a homeodomain-containing transcription factor chimera recurrently detected in leukaemias, are essential for establishing liquid–liquid phase separation (LLPS) puncta of chimera and for inducing leukaemic transformation. LLPS of NUP98–HOXA9 not only promotes chromatin occupancy of chimera transcription factors, but also is required for the formation of a broad “super-enhancer”-like binding pattern typically seen at leukaemogenic genes, which potentiates transcriptional activation. An artificial HOX chimera, created by replacing the phenylalanine and glycine repeats of NUP98 with an unrelated LLPS-forming IDR of the FUS protein, had similar enhancing effects on the genome-wide binding and target gene activation of the chimera. This report describes a proof-of-principle example in which cancer acquires mutation to establish oncogenic transcription factor condensates via phase separation, which simultaneously enhances their genomic targeting and induces organization of aberrant three-dimensional chromatin structure during tumor transformation. Supported by ORIP (S10OD018445).
Protection of Newborn Macaques by Plant-Derived HIV Broadly Neutralizing Antibodies: A Model for Passive Immunotherapy During Breastfeeding
Rosenberg et al., Journal of Virology. 2021.
https://doi.org/10.1128/JVI.00268-21
Preventing vertical transmission of HIV to newborns is an unmet medical need in resource poor countries. Using a breastfeeding macaque model with multiple simian-human immunodeficiency virus challenge, researchers assessed the protective efficacy of two human broadly neutralizing antibodies (bnAbs) against HIV, PGT121 and VRC07-523, which are produced by a plant expression system. Despite the transient presence of plasma viral RNA, the bnAbs prevented productive infection in all newborns with no sustained plasma viremia, compared to viral loads ranging from 103 to 5x108 in four untreated controls. Thus, plant-expressed antibodies show promise as passive immunoprophylaxis in a breastfeeding model in newborns. Supported by ORIP (U42OD023038, P51OD011092) and NIAID.
Tissue-Specific Transcriptional Profiling of Plasmacytoid Dendritic Cells Reveals a Hyperactivated State in Chronic SIV Infection
Lee et al., PLOS Pathogens. 2021.
https://doi.org/10.1371/journal.ppat.1009674
Persistent immune activation is an obstacle to optimal health for people living with HIV. Using RNA sequencing, researchers investigated the immunostimulatory potential of plasmacytoid dendritic cells (pDCs) in chronic SIV infection in rhesus macaques. They observed that pDCs have highly activated profiles in these animals. In contrast, pDCs from SIV-infected sooty mangabeys (natural hosts for SIV) had expression profiles similar to uninfected animals. In chronically infected rhesus macaques, interferon alpha transcripts were readily detected in lymph node-homing pDCs, but not those from blood. Therefore, pDCs are a major producer of type-I interferon in chronic SIV infection and could be a useful immunotherapy target. Supported by ORIP (R24OD010445, P51OD011132, P51OD011092, S10OD026799) and NIAID.
Immune Inactivation of Anti-Simian Immunodeficiency Virus Chimeric Antigen Receptor T Cells in Rhesus Macaques
Haeseleer et al., Molecular Therapy–Methods & Clinical Development. 2021.
https://doi.org/10.1016/j.omtm.2021.06.008
Chimeric antigen receptor (CAR) T cell therapies are under development as potential HIV cures. Researchers found that CAR T cells expressing a single-chain variable fragment (scFv) that recognizes V1 or V3 of the SIV envelope eliminated SIV-infected T cells in vitro. However, in vivo infusion of these CAR T cells in rhesus macaques resulted in no detectable antiviral activity. Anti-SIV IgG antibodies in the SIV-infected animals were associated with inhibited CAR T cell effector functions. Thus, lack of in vivo efficacy of CAR T cells might be due to antibodies blocking the interaction between the CAR scFv and its epitope. Supported by ORIP (P51OD011092) and NIAID.
Gut Germinal Center Regeneration and Enhanced Antiviral Immunity by Mesenchymal Stem/Stromal Cells
Weber et al., JCI Insight. 2021.
https://doi.org/10.1172/jci.insight.149033
Researchers investigated the effects of mesenchymal stem/stromal cell (MSC) infusions on gut mucosal recovery, antiviral immunity, and viral suppression in SIV-infected rhesus macaques. MSC treatment heightened virus-specific responses and reduced viral load. Clearance of SIV-positive cells from gut mucosal effector sites was correlated with regeneration of germinal centers, restoration of follicular B cells and T follicular helper cells, and enhanced antigen presentation by viral trapping within the follicular dendritic cell network. These changes were associated with enhanced gene expression for type I/II interferon signaling, B cell proliferation, and interleukin 7. MSC treatment also activated metabolic pathways associated with enhanced immunity and viral reduction. Supported by ORIP (P51OD011107) and NIAID.
Western-Style Diet Consumption Impairs Maternal Insulin Sensitivity and Glucose Metabolism During Pregnancy in a Japanese Macaque Model
Elsakr et al., Scientific Reports. 2021.
https://www.nature.com/articles/s41598-021-92464-w
Using a Japanese macaque model, investigators assessed the metabolic effects of obesity and a calorically dense, Western-style diet (WSD; 36.3% fat), either alone or together, on maternal glucose tolerance and insulin levels in dams during pregnancy (n = 95 females followed over multiple pregnancies [n = 273]). With prolonged WSD feeding, multiple diet switches, and/or increasing age and parity, WSD was associated with increasingly higher insulin levels during glucose tolerance testing, indicative of insulin resistance. The results suggest that prolonged or recurrent calorically dense WSD and/or increased parity, rather than obesity per se, drive excess insulin resistance and metabolic dysfunction. Supported by ORIP (P51OD011092), NIDDK and NIMH.
In Vitro and In Vivo Functions of SARS-CoV-2 Infection-Enhancing and Neutralizing Antibodies
Li et al., Cell. 2021.
https://doi.org/10.1016/j.cell.2021.06.021
Antibody-dependent enhancement of infection is a concern for clinical use of antibodies. Researchers isolated neutralizing antibodies against the receptor-binding domain (RBD) or N-terminal domain (NTD) of SARS-CoV-2 spike from COVID-19 patients. Cryo-electron microscopy of RBD and NTD antibodies demonstrated function-specific binding modes. RBD and NTD antibodies mediated both neutralization and infection enhancement in vitro. However, infusion of these antibodies into mice or macaques resulted in suppression of virus replication, demonstrating that antibody-enhanced infection in vitro does not necessarily predict enhanced infection in vivo. RBD-neutralizing antibodies having cross-reactivity against coronaviruses were protective against SARS-CoV-2, the most potent of which was DH1047. Supported by ORIP (P40OD012217, U42OD021458, S10OD018164), NIAID, NCI, NIGMS, and NIH Common Fund.
SARS-CoV-2 Vaccines Elicit Durable Immune Responses in Infant Rhesus Macaques
Garrido et al., Science Immunology. 2021.
https://immunology.sciencemag.org/content/6/60/eabj3684
The immunogenicity of two SARS-CoV-2 vaccines was evaluated in both sexes of infant rhesus macaques (n=8/group). Neither vaccine, stabilized prefusion SARS-CoV-2 S-2P spike (S) protein encoded by mRNA encapsulated in lipid nanoparticles or the purified S protein mixed with 3M-052, a synthetic TLR7/8 agonist in a squalene emulsion, induced adverse effects. Both elicited high magnitude neutralizing antibody titers peaking at week 6. S-specific T cell responses were dominated by IL-17, IFN-γ, or TNF-α. Antibody and cellular responses were stable through week 22. These data provide proof-of concept for a pediatric SARS-CoV-2 vaccine with the potential for durable immunity to decrease transmission of COVID-19. Supported by ORIP (P51OD011107), NIAID, and NCI.
Thioesterase Superfamily Member 1 Undergoes Stimulus-Coupled Conformational Reorganization to Regulate Metabolism in Mice
Li et al., Nature Communications. 2021.
https://doi.org/10.1038/s41467-021-23595-x
Thermogenesis is suppressed in brown adipose tissue by thioesterase superfamily member 1 (Them1), a long chain fatty acyl-CoA thioesterase. Them1 is highly upregulated by cold ambient temperature, where it reduces fatty acid availability and limits thermogenesis. Investigators show that Them1 regulates metabolism by undergoing conformational changes in response to β-adrenergic stimulation that alter Them1 intracellular distribution. Them1 forms metabolically active puncta near lipid droplets and mitochondria. Upon stimulation, Them1 is phosphorylated at the N-terminus, inhibiting puncta formation and activity, and resulting in a diffuse intracellular localization. Investigators show that Them1 puncta are biomolecular condensates that are inhibited by phosphorylation. Them1 forms intracellular biomolecular condensates that limit fatty acid oxidation and suppress thermogenesis. When energy is demanded, the condensates are disrupted by phosphorylation to allow for maximal thermogenesis. The stimulus-coupled reorganization of Them1 provides fine-tuning of thermogenesis and energy expenditure. Supported by ORIP (S10OD019988) and others.