Selected Grantee Publications
Negative Inotropic Mechanisms of β-cardiotoxin in Cardiomyocytes by Depression of Myofilament ATPase Activity without Activation of the Classical β-Adrenergic Pathway
Lertwanakarn et al., Scientific Reports. 2021.
https://www.nature.com/articles/s41598-021-00282-x
Beta-cardiotoxin (β-CTX) from the king cobra venom (Ophiophagus hannah) was previously proposed as a novel β-adrenergic blocker. However, the involvement of β-adrenergic signaling by this compound has never been elucidated. The objectives of this study were to investigate the underlying mechanisms of β-CTX as a β-blocker and its association with the β-adrenergic pathway. Healthy Sprague Dawley rats were used for cardiomyocytes isolation. In summary, the negative inotropic mechanism of β-CTX was discovered. β-CTX exhibits an atypical β-blocker mechanism. These properties of β-CTX may benefit in developing a novel agent aid to treat hypertrophic cardiomyopathy. Supported by ORIP (P40OD010960) and NHLBI.
Comparative Cellular Analysis of Motor Cortex in Human, Marmoset and Mouse
Bakken et al., Nature. 2021.
https://pubmed.ncbi.nlm.nih.gov/34616062/
Investigators used high-throughput transcriptomic and epigenomic profiling of more than 450,000 single nuclei in humans, marmosets, and mice, to characterize the cellular makeup of the primary motor cortex (M1), which exhibits similarities that mirror evolutionary distance and are consistent between the transcriptome and epigenome. Despite the overall conservation, many species-dependent specializations are apparent. These results demonstrate the robust molecular foundations of cell-type diversity in M1 across mammals and point to the genes and regulatory pathways responsible for the functional identity of cell types and their species-specific adaptations. Supported by ORIP (P51OD010425), NIMH, NCATS, NINDS, and NIDA.
Safety, Pharmacokinetics and Antiviral Activity of PGT121, a Broadly Neutralizing Monoclonal Antibody Against HIV-1: A Randomized, Placebo-Controlled, Phase 1 Clinical Trial
Stephenson et al., Nature Medicine. 2021.
https://doi.org/10.1038/s41591-021-01509-0
Researchers carried out a double-blind trial of one administration of the HIV-1 V3-glycan-specific antibody (Ab) PGT121 in HIV-uninfected and HIV-infected adults on antiretroviral therapy (ART), as well as an open-label trial of one infusion of PGT121 in viremic HIV-infected adults not on ART. The investigators observed no treatment-related serious adverse events among the 48 participants, and neutralizing anti-drug Abs were not elicited. PGT121 reduced plasma HIV RNA by a median of 1.77 log in viremic participants. Two individuals experienced ART-free viral suppression for ≥168 days following Ab infusion. These findings motivate further investigation of Ab-based therapeutic strategies for long-term HIV suppression. Supported by ORIP (R01OD024917, R01OD011095), NIAID, and NCATS.
MIC-Drop: A Platform for Large-scale In Vivo CRISPR Screens
Parvez et al., Science. 2021.
https://pubmed.ncbi.nlm.nih.gov/34413171/
CRISPR screens in animals are challenging because generating, validating, and keeping track of large numbers of mutant animals is prohibitive. These authors introduce Multiplexed Intermixed CRISPR Droplets (MIC-Drop), a platform combining droplet microfluidics, single-needle en masse CRISPR ribonucleoprotein injections, and DNA barcoding to enable large-scale functional genetic screens in zebrafish. In one application, they showed that MIC-Drop could identify small-molecule targets. Furthermore, in a MIC-Drop screen of 188 poorly characterized genes, they discovered several genes important for cardiac development and function. With the potential to scale to thousands of genes, MIC-Drop enables genome-scale reverse genetic screens in model organisms. Supported by ORIP (R24OD017870), NIGMS, and NHLBI.
Factor XII Plays a Pathogenic Role in Organ Failure and Death in Baboons Challenged with Staphylococcus aureus
Silasi et al., Blood. 2021.
https://pubmed.ncbi.nlm.nih.gov/33598692/
Activation of coagulation factor (F) XI promotes multiorgan failure in rodent models of sepsis and in a baboon model for lethal systemic inflammation induced by infusion of heat-inactivated Staphylococcus aureus. The authors used the anticoagulant FXII-neutralizing antibody 5C12 to verify the mechanistic role of FXII. Inhibition of FXII prevented fever, terminal hypotension, respiratory distress, and multiorgan failure. All animals receiving 5C12 had milder and transient clinical symptoms; untreated control animals suffered irreversible multiorgan failure. This study confirms their previous finding that at least two enzymes of FXIa and FXIIa play critical roles in the development of an acute and terminal inflammatory response. Supported by ORIP (P40OD024628), NIAID, NHLBI, and NIGMS.
Mineralocorticoid Receptor Blockade Normalizes Coronary Resistance in Obese Swine Independent of Functional Alterations in Kv Channels
Goodwill et al., Basic Research in Cardiology. 2021.
https://pubmed.ncbi.nlm.nih.gov/34018061/
Impaired coronary microvascular function (e.g., reduced dilation and coronary flow reserve) predicts cardiac mortality in obesity. Mineralocorticoid receptor (MR) antagonism improves coronary microvascular function in obese humans and animals. Inhibition of Kv channels reduced coronary blood flow and augmented coronary resistance under baseline conditions in lean but not obese swine and had no impact on hypoxemic coronary vasodilation. MR blockade prevented obesity-associated coronary arteriolar stiffening independent of cardiac capillary density and changes in cardiac function. These data indicate that chronic MR inhibition prevents increased coronary resistance in obesity independent of Kv channel function and is associated with mitigation of obesity-mediated coronary arteriolar stiffening. Supported by ORIP (U42OD011140, S10OD023438), NHLBI, and NIBIB.
A Participant-Derived Xenograft Model of HIV Enables Long-Term Evaluation of Autologous Immunotherapies
McCann et al., Journal of Experimental Medicine. 2021.
https://doi.org/10.1084/jem.20201908
HIV-specific CD8+ T cells partially control viral replication but rarely provide lasting protection due to immune escape. Investigators showed that engrafting NSG mice with memory CD4+ T cells from HIV+ donors enables evaluation of autologous T cell responses while avoiding graft-versus-host disease. Treating HIV-infected mice with clinically relevant T cell products reduced viremia. In vivo activity was significantly enhanced when T cells were engineered with surface-conjugated nanogels carrying an Interleukin-15 superagonist but was ultimately limited by the pervasive selection of escape mutations, recapitulating human patterns. This “participant-derived xenograft” model provides a powerful tool for developing T cell-based therapies for HIV. Supported by ORIP (R01OD011095), NIAID, NIDA, NIMH, NINDS, and NCATS.
Cell-Specific Transcriptional Control of Mitochondrial Metabolism by TIF1γ Drives Erythropoiesis
Rossmann et al., Science. 2021.
https://pubmed.ncbi.nlm.nih.gov/33986176/
Transcription and metabolism both influence cell function but dedicated transcriptional control of metabolic pathways that regulate cell fate has rarely been defined. The authors discovered that inhibition of the pyrimidine biosynthesis enzyme dihydroorotate dehydrogenase (DHODH) rescues erythroid differentiation in bloodless zebrafish moonshine (mon) mutant embryos defective for transcriptional intermediary factor 1 gamma (tif1γ). Upon tif1γ loss, CoQ levels are reduced, and a high succinate/α-ketoglutarate ratio leads to increased histone methylation. A CoQ analog rescues mon's bloodless phenotype. These results demonstrate that mitochondrial metabolism is a key output of a lineage transcription factor that drives cell fate decisions in the early blood lineage. Supported by ORIP (R24OD017870), NIGMS, NHLBI, and NCI.
'Enhancing' Red Cell Fate Through Epigenetic Mechanisms
Rossmann and Zon et al., Current Opinion in Hematology. 2021.
https://pubmed.ncbi.nlm.nih.gov/33741760/
Transcription of erythroid-specific genes is regulated by the three-dimensional (3D) structure and composition of chromatin, which changes during erythroid differentiation. These authors address recent developments delineating the interface of chromatin regulation and erythroid-specific lineage transcription. They survey the erythroid chromatin landscape, erythroid enhancer-promotor interactions, super-enhancer functionality, the role of chromatin modifiers and epigenetic crosstalk, as well as the progress in mapping red blood cell (RBC) trait-associated genetic variants within cis-regulatory elements (CREs) identified in genome-wide association study (GWAS) efforts. New emerging technologies allow investigation of small cell numbers have advanced our understanding of chromatin dynamics during erythroid differentiation in vivo. Supported by ORIP (R24OD017870) and NHLBI.
Natural Killer Cells Activated Through NKG2D Mediate Lung Ischemia-Reperfusion Injury
Calabrese et al., Journal of Clinical Investigation. 2021.
https://www.jci.org/articles/view/137047
Pulmonary ischemia-reperfusion injury (IRI) causes early mortality and has no effective therapies. While natural killer (NK) cells are innate lymphocytes capable of recognizing injured cells, their roles in acute lung injury are incompletely understood. Here, investigators demonstrated that NK cells were increased in frequency and cytotoxicity in 2 different IRI mouse models. They showed that NK cells trafficked to the lung tissue from peripheral reservoirs and were more mature within lung tissue. Acute lung ischemia-reperfusion injury was blunted in a NK cell–deficient mouse strain but restored with adoptive transfer of NK cells. In human lung tissue, NK cells were increased at sites of ischemia-reperfusion injury and activated NK cells were increased in prospectively-collected human bronchoalveolar lavage in subjects with severe IRI. These data support a causal role for recipient peripheral NK cells in pulmonary IRI via NK cell NKG2D receptor ligation. Therapies targeting NK cells may hold promise in acute lung injury. Supported by ORIP (S10OD026940), NHLBI, and NIDDK.