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Vaccination Induces Broadly Neutralizing Antibody Precursors to HIV gp41
Schiffner et al., Nature Immunology. 2024.
https://pubmed.ncbi.nlm.nih.gov/38816615
Primary immunogens that induce rare broadly neutralizing antibody (bnAb) precursor B cells are needed to develop vaccines against viruses of high antigenic diversity. 10E8-class bnAbs must possess a long, heavy chain complementarity determining region 3 (HCDR3) with a specific binding motif. Researchers developed germline-targeting epitope scaffolds with an affinity for 10E8-class precursors that exhibited epitope structural mimicry and bound bnAb-precursor human naive B cells in ex vivo screens. Protein nanoparticles induced bnAb-precursor responses in stringent mouse models and rhesus macaques, and mRNA-encoded nanoparticles triggered similar responses in mice. This study showed that germline-targeting epitope scaffold nanoparticles can elicit rare bnAb-precursor B cells with predefined binding specificities and HCDR3 features. Supported by ORIP (P51OD011132, U42OD011023), NIAID, and NIGMS.
Natural Killer–Like B Cells Are a Distinct but Infrequent Innate Immune Cell Subset Modulated by SIV Infection of Rhesus Macaques
Manickam et al., PLOS Pathogens. 2024.
https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1012223
Natural killer–like B (NKB) cells express both natural killer (NK) and B cell receptors. Intracellular signaling proteins and trafficking markers were expressed differentially on naive NKB cells. CD20+ NKG2A/C+ NKB cells were identified in organs and lymph nodes of naive rhesus macaques (RMs). Single-cell RNA sequencing (scRNAseq) of sorted NKB cells confirmed that NKB cells are unique, and transcriptomic analysis of naive splenic NKB cells by scRNAseq showed that NKB cells undergo somatic hypermutation and express Ig receptors, similar to B cells. Expanded NKB frequencies were observed in RM gut and buccal mucosa after simian immunodeficiency virus (SIV) infection, and mucosal and peripheral NKB cells were associated with colorectal cytokine milieu and oral microbiome changes. NKB cells gated on CD3-CD14-CD20+NKG2A/C+ cells were inclusive of transcriptomically conventional B and NK cells in addition to true NKB cells, confounding accurate phenotyping and frequency recordings. Supported by ORIP (P51OD011132, S10OD026799) and NIAID.
Integrin αvβ3 Upregulation in Response to Nutrient Stress Promotes Lung Cancer Cell Metabolic Plasticity
Nam, Cancer Research. 2024.
https://pubmed.ncbi.nlm.nih.gov/38588407/
Tumor-initiating cells can survive in harsh environments via stress tolerance and metabolic flexibility; studies on this topic can yield new targets for cancer therapy. Using cultured cells and live human surgical biopsies of non-small cell lung cancer, researchers demonstrated that nutrient stress drives a metabolic reprogramming cascade that allows tumor cells to thrive despite a nutrient-limiting environment. This cascade results from upregulation of integrin αvβ3, a cancer stem cell marker. In mice, pharmacological or genetic targeting prevented lung cancer cells from evading the effects of nutrient stress, thus blocking tumor initiation. This work suggests that this molecular pathway leads to cancer stem cell reprogramming and could be linked to metabolic flexibility and tumor initiation. Supported by ORIP (K01OD030513), NCI, NIGMS, and NINDS.
Transcriptome- and Proteome-Wide Effects of a Circular RNA Encompassing Four Early Exons of the Spinal Muscular Atrophy Genes
Luo, Scientific Reports. 2024.
https://pubmed.ncbi.nlm.nih.gov/38714739/
Spinal muscular atrophy (SMA) is a leading genetic cause of mortality in infants and often results from a deficiency of deletions of or mutations in the SMN1 gene. In this study, researchers report the transcriptome- and proteome-wide effects of overexpression of C2A‑2B3-4, a circular RNA produced by SMN1 and SMN2, in cells. They report that C2A-2B-3-4 is associated with expression of genes associated with chromatin remodeling, transcription, spliceosome function, ribosome biogenesis, lipid metabolism, cytoskeletal formation, cell proliferation, and neuromuscular junction formation. More work is needed to investigate the role of these genes in processes associated with SMA and other pathological conditions, including cancer and male infertility. Supported by ORIP (T35OD027967) and NINDS.
CD8+ T Cell Targeting of Tumor Antigens Presented by HLA-E
Iyer, Science Advances. 2024.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11086602/
Researchers have hypothesized that human leukocyte antigen-E (HLA-E)–positive cancer cells could be targeted by HLA-E–restricted CD8+ T cells. In this study, the authors assessed whether major histocompatibility complex E (MHC-E) expression by cancer cells can be targeted for MHC-E–restricted T cell control. Using male rhesus macaques, they found that a cytomegalovirus can be used as a vector to generate specific immune cells that can target cancer cells. The authors conclude that targeting HLA-E with restricted, specific CD8+ T cells could offer a new approach for immunotherapy of prostate cancer. Overall, this study supports the concept of a cancer vaccine. Supported by ORIP (P51OD011092) and NIAID.
A Revamped Rat Reference Genome Improves the Discovery of Genetic Diversity in Laboratory Rats
de Jong, Cell Genomics. 2024.
https://www.cell.com/cell-genomics/fulltext/S2666-979X(24)00069-7
Rattus norvegicus has been used in many fields of study related to human disease; its genome was sequenced shortly after the genomes of Homo sapiens and Mus musculus. Investigators report extensive analyses of the improvements in mRatBN7.2, compared with the previous version. They conducted a broad analysis of a whole-genome sequencing data set of 163 samples from 120 inbred rat strains and substrains. Several additional resources have been created. This new assembly and its associated resources create a more solid platform for research on the many dimensions of physiology, behavior, and pathobiology of rats and can provide more reliable and meaningful translation of findings to human populations. Supported by ORIP (R24OD024617), NHGRI, NHLBI, and NIDA.
Potent HPIV3-Neutralizing IGHV5-51 Antibodies Identified from Multiple Individuals Show L Chain and CDRH3 Promiscuity
Abu-Shmais et al., Journal of Immunology. 2024.
https://pubmed.ncbi.nlm.nih.gov/38488511/
Human parainfluenza virus 3 fusion glycoprotein (HPIV3 F), responsible for facilitating viral entry into host cells, is a major target of neutralizing antibodies that inhibit infection. More work is needed to understand these dynamics. Researchers characterized the genetic signatures, epitope specificity, neutralization potential, and publicness of HPIV3-specific antibodies identified across multiple individuals. From this work, they identified 12 potently neutralizing antibodies targeting three nonoverlapping epitopes on HPIV3 F. Six of the antibodies used immunoglobulin heavy variable gene, IGHV 5-51. These antibodies used different L chain variable genes (VL) and diverse H chain CDR 3 (CDRH3) sequences. These findings help elucidate the genetic and functional characteristics of HPIV3-neutralizing antibodies and indicate the existence of a reproducible H chain variable–dependent antibody response associated with VL and CDRH3 promiscuity. Supported by ORIP (K01OD036063), NCATS, NCI, NEI, NIAID, and NIDDK.
Murine MHC-Deficient Nonobese Diabetic Mice Carrying Human HLA-DQ8 Develop Severe Myocarditis and Myositis in Response to Anti-PD-1 Immune Checkpoint Inhibitor Cancer Therapy
Racine et al., Journal of Immunology. 2024.
Myocarditis has emerged as a relatively rare but often lethal autoimmune complication of checkpoint inhibitor (ICI) cancer therapy, and significant mortality is associated with this phenomenon. Investigators developed a new mouse model system that spontaneously develops myocarditis. These mice are highly susceptible to myocarditis and acute heart failure following anti-PD-1 ICI-induced treatment. Additionally, the treatment accelerates skeletal muscle myositis. The team performed characterization of cardiac and skeletal muscle T cells using histology, flow cytometry, adoptive transfers, and RNA sequencing analyses. This study sheds light on underlying immunological mechanisms in ICI myocarditis and provides the basis for further detailed analyses of diagnostic and therapeutic strategies. Supported by ORIP (U54OD020351, U54OD030187), NCI, NIA, NIDDK, and NIGMS.
Obesity Causes Mitochondrial Fragmentation and Dysfunction in White Adipocytes Due to RalA Activation
Xia et al., Nature Metabolism. 2024.
https://pubmed.ncbi.nlm.nih.gov/38286821/
This study presents a molecular mechanism for mitochondrial dysfunction as a characteristic trait of obesity. Chronic activation of the small GTPase RalA in inguinal white adipocytes (iWAT), in male mice fed a high-fat diet (HFD) represses energy expenditure by shifting mitochondrial dynamics toward excessive fission, contributing to weight gain and metabolic dysfunction. Targeted deletion of RalA in iWAT attenuated HFD-induced obesity due to increased energy expenditure and mitochondrial oxidative phosphorylation. Mechanistically, RalA dephosphorylates inhibitory Serine637 on fission protein Drp1, leading to excessive fission in adipocytes and mitochondrial fragmentation. Expression of a human homolog of Drp1—DNM1L—in adipose tissue is positively correlated with obesity and insulin resistance. These findings open avenues to investigate RalA-Drp1 axis in energy homeostasis. Supported by ORIP (S10OD023527), NCI, NHLBI, and NIDDK.
Cdk8/CDK19 Promotes Mitochondrial Fission Through Drp1 Phosphorylation and Can Phenotypically Suppress Pink1 Deficiency in Drosophila
Liao et al., Nature Communications. 2024.
https://www.nature.com/articles/s41467-024-47623-8
Pink1 is a mitochondrial kinase implicated in Parkinson’s disease and is conserved among humans, rodents, and flies. In this study, researchers found that Cdk8 in Drosophila (i.e., the orthologue of vertebrate CDK8 and CDK19) promotes the phosphorylation of Drp1 (i.e., a protein required for mitochondrial fission) at the same residue as Pink1. Cdk8 is expressed in both the cytoplasm and nucleus, and neuronal loss of Cdk8 reduces fly life span and causes bang sensitivity and elongated mitochondria in both muscles and neurons. Overexpression of Cdk8 suppresses elevated levels of reactive oxygen species, mitochondrial dysmorphology, and behavioral defects in flies with low levels of Pink1. These findings suggest that Cdk8 regulates Drp1-mediated mitochondrial fission in a similar manner as Pink1 and may contribute to the development of Parkinson’s disease. Supported by ORIP (R24OD022005, R24OD031447, P40OD018537, P40OD010949), NICHD, and NINDS.