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- Rare Diseases
- Vaccines/Therapeutics
Evaluating a New Class of AKT/mTOR Activators for HIV Latency-Reversing Activity Ex Vivo and In Vivo
Gramatica et al., Journal of Virology. 2021.
https://doi.org/10.1128/JVI.02393-20
Activation of latent HIV-1 expression could benefit many HIV cure strategies. Researchers evaluated two AKT/mTOR activators, SB-216763 and tideglusib, as a potential new class of LRAs. The drugs reactivated latent HIV-1 present in blood samples from aviremic individuals on antiretroviral therapy without causing T cell activation or impaired effector function of cytotoxic T lymphocytes or NK cells. When tested in vivo in monkeys, tideglusib showed unfavorable pharmacodynamic properties and did not reverse SIV latency. The discordance between the ex vivo and in vivo results underscores the importance of developing novel LRAs that allow systemic drug delivery to relevant anatomical compartments. Supported by ORIP (P51OD011092), NIAID, NIGMS, NIMH, and NCI.
BNT162b Vaccines Protect Rhesus Macaques from SARS-CoV-2
Vogel et al., Nature. 2021.
https://www.nature.com/articles/s41586-021-03275-y
The preclinical development of two BNT162b vaccine candidates, which contain lipid-nanoparticle formulated nucleoside-modified mRNA encoding SARS-CoV-2 spike glycoprotein-derived immunogens, was performed in rhesus macaques at the Southwest National Primate Research Center (SNPRC). BNT162b1 encodes a soluble, secreted, trimerised receptor-binding domain. BNT162b2 encodes the full-length transmembrane spike glycoprotein, locked in its prefusion conformation. Prime/boost vaccination of rhesus macaques with BNT162b candidates elicits SARS-CoV-2 neutralizing antibody titers that are 8.2 to 18.2 times that of a SARS-CoV-2 convalescent human serum panel. The vaccine candidates protected macaques from SARS-CoV-2 challenge, with BNT162b2 protecting the lower respiratory tract from the presence of viral RNA and with no evidence of disease enhancement. The BNT162b2 vaccine recently received emergency use authorization from FDA and is being administered within the United States. The SNPRC is supported by ORIP (P51OD011103).
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.
Modified Vaccinia Ankara Vector-Based Vaccine Protects Macaques from SARS-CoV-2 Infection, Immune Pathology and Dysfunction in the Lung
Routhu et al., Immunity. 2021.
https://doi.org/10.1016/j.immuni.2021.02.001
Any SARS-CoV-2 vaccine may have limitations such as need for ultracold storage, poor induction of CD8+ T cell response, or lack of cross-reactivity with emerging strains. Thus, multiple vaccines may be needed to bring COVID-19 under control. Using rhesus macaques, researchers showed that a modified vaccinia Ankara (MVA) vector-based SARS-CoV-2 vaccine expressing prefusion-stabilized spike protein induced strong neutralizing antibody and CD8+ T cell responses. The vaccine protected macaques from SARS-CoV-2 infection as well as infection-induced inflammation and B cell abnormalities in the lung. These results are promising considering the excellent safety and performance of MVA vector-based vaccines for other pathogens. Supported by ORIP (P51OD011132, S10OD026799) and NIAID.
Thresholds for Post-Rebound SHIV Control after CCR5 Gene-Edited Autologous Hematopoietic Cell Transplantation
Cardozo-Ojeda et al., eLife. 2021.
https://elifesciences.org/articles/57646
Investigators developed a mathematical model to project the minimum threshold of C-C chemokine receptor type 5 (CCR5) gene-edited cells necessary for a functional cure from HIV. This was based on blood T cell reconstitution and plasma simian-HIV (SHIV) dynamics from SHIV-1157ipd3N4-infected juvenile pig-tailed macaques that underwent autologous transplantation with CCR5 gene editing. The model predicts that viral control can be obtained following analytical treatment interruption (ATI) when: (1) transplanted hematopoietic stem and progenitor cells (HSPCs) are at least fivefold higher than residual endogenous HSPCs after total body irradiation and (2) the fraction of protected HSPCs in the transplant achieves a threshold (76–94%) sufficient to overcome transplantation-dependent loss of SHIV immunity. Under these conditions, if ATI is withheld until transplanted gene-modified cells engraft and reconstitute to a steady state, spontaneous viral control is projected to occur. Supported by ORIP (P51OD010425), NCATS and NIAID.
Deploying MMEJ using MENdel in Precision Gene Editing Applications for Gene Therapy and Functional Genomics
Martínez-Gálvez et al., Nucleic Acids Research. 2021.
https://academic.oup.com/nar/article/49/1/67/6030233
Gene-editing experiments commonly elicit the error-prone non-homologous end joining for DNA double-strand break (DSB) repair. Martinez-Galvez et al. compared three DSB repair prediction algorithms - MENTHU, inDelphi, and Lindel. MENTHU correctly identified 46% of all PreMAs available, a ∼2- and ∼60-fold sensitivity increase compared to inDelphi and Lindel, respectively. The investigators report the new algorithm MENdel, a combination of MENTHU and Lindel, that achieves the most predictive coverage of homogeneous out-of-frame mutations. They suggest that the use of MENdel helps researchers use MMEJ at scale for reverse genetics screenings to be viable for nearly all loss-of-function based gene editing therapeutic applications. Supported by ORIP (R24OD020166) and NIGMS.
Increased Proviral DNA in Circulating Cells Correlates With Plasma Viral Rebound in SIV-Infected Rhesus Macaques after Antiretroviral Therapy Interruption
Ziani et al., Journal of Virology. 2021.
https://jvi.asm.org/content/early/2021/01/05/JVI.02064-20
Investigators longitudinally tracked dynamic decay of cell-associated viral RNA/DNA in systemic and lymphoid tissues in SIV-infected rhesus macaques on prolonged combined antiretroviral therapy (cART) to evaluate predictors of viral rebound after treatment cessation. Suppressive cART substantially reduced plasma SIV RNA, cell-associated unspliced, and multiply spliced SIV RNA to undetectable levels, yet viral DNA remained detectable in systemic tissues and lymphoid compartments throughout cART. A rapid increase of integrated proviral DNA in peripheral mononuclear cells was detected once cART was withdrawn, accompanied by the emergence of detectable plasma viral load. The increase of peripheral proviral DNA post cART interruption correlated with the emergence and degree of viral rebound. These results suggest that measuring total viral DNA in SIV infection may be a relatively simple surrogate marker of reservoir size, and may predict viral rebound after treatment interruption, and inform treatment strategies. Supported by ORIP (P51OD011104), NIAID and NICHD.
Antibody-Mediated Depletion of Viral Reservoirs is Limited in SIV-Infected Macaques Treated Early With Antiretroviral Therapy
Swanstrom et al., Journal of Clinical Investigation. 2021.
https://doi.org/10.1172/JCI142421
Virus-specific strategies to target the latent HIV reservoir in individuals on combination antiretroviral therapy (cART) have been limited by inefficient induction of viral protein expression. Researchers used rhesus macaques to investigate an antibody-mediated reservoir targeting strategy, targeting the CD4 molecule rather than a viral protein, to deplete potential viral target cells irrespective of infection status. Despite profound CD4+ T cell depletion in blood and lymph nodes, time to viral rebound following cART cessation was not delayed in anti-CD4 treated animals compared with controls, likely due to the limited antibody-mediated cell depletion that occurred in rectal tissue and lymphoid follicles. Supported by ORIP (R24OD010976), NCI, and NIAID.
The Immune Landscape in Tuberculosis Reveals Populations Linked to Disease and Latency
Esaulova et al., Cell Host Microbe. 2020.
https://pubmed.ncbi.nlm.nih.gov/33340449/
Mycobacterium tuberculosis infection of adult rhesus macaques (RMs), predominantly males (81%), recapitulates both latent (LTBI) and active pulmonary TB (PTB) observed in humans. The immune characterization in lungs of RMs with PTB exhibited an influx of plasmacytoid dendritic cells, an interferon-responsive macrophage population, and activated T cell responses. In contrast, a CD27+ natural killer (NK) cell subset accumulated in the lungs of RMs with LTBI. This NK cell population was also detected in the circulation of humans with LTBI. This characterization of lung immune cells enhances our understanding of TB immunopathogenesis and provides potential targets for therapies and vaccines for TB control. Supported by ORIP (P51OD011104 and P51OD011133), NHLBI, and NIAID.
Lipocalin-2 Is an Anorexigenic Signal in Primates
Petropoulou et al., eLife. 2020.
https://doi.org/10.7554/eLife.58949
The hormone lipocalin-2 (LCN2) suppresses food intake in mice. Researchers demonstrated that LCN2 increases after a meal and reduces hunger in people with normal weight or overweight, but not in obese individuals. The researchers also showed that LCN2 crosses the blood-brain barrier and binds to the hypothalamus in vervet monkeys. LCN2 was found to bind to the hypothalamus in human, baboon, and rhesus macaque brain sections. When injected into vervets, LCN2 suppressed food intake and lowered body weight without toxic effects in short-term experiments. These findings lay the groundwork to investigate whether LCN2 might be a useful treatment for obesity. Supported by ORIP (P40OD010965), NCATS, NIDDK, NIA, and NHLBI.