Lone et al. characterize mutations in a subunit of serine palmitoyltransferase that cause childhood-onset amyotrophic lateral sclerosis; and define specific lipid signatures and defects in ceramide synthesis. The cover art depicts ALS motor neurons drowning in a flood of sphingolipids from a sphingolipid-synthesizing enzyme cloud. Image credit: Sofia Ahola.
Hematopoietic stem cells, regulated by their microenvironment (or “niche”), sustain the production of mature blood and immune cells. Leukemia cells remodel the microenvironment to enhance their survival, which is accompanied by the loss of support for normal hematopoiesis in hematologic malignancies. Extracellular vesicles (EVs) mediate intercellular communication in physiological and pathological conditions, and deciphering their functions in cell-cell interactions in the ecosystem can highlight potential therapeutic targets. In this Review, we illustrate the utility of EVs derived from various cell types, focusing on the biological molecules they contain and the behavioral alterations they can induce in recipient cells. We also discuss the potential for clinical application in hematologic malignancies, including EV-based therapeutic regimens, drug delivery via EVs, and the use of EVs (or their cargoes) as biomarkers.
Guohuan Sun, Quan Gu, Junke Zheng, Hui Cheng, Tao Cheng
Germline loss-of-function mutations of the VHL tumor suppressor gene cause von Hippel–Lindau disease, which is associated with an increased risk of hemangioblastomas, clear cell renal cell carcinomas (ccRCCs), and paragangliomas. This Review describes mechanisms involving the VHL gene product in oxygen sensing, protein degradation, and tumor development and current therapeutic strategies targeting these mechanisms. The VHL gene product is the substrate recognition subunit of a ubiquitin ligase that targets the α subunit of the heterodimeric hypoxia-inducible factor (HIF) transcription factor for proteasomal degradation when oxygen is present. This oxygen dependence stems from the requirement that HIFα be prolyl-hydroxylated on one (or both) of two conserved prolyl residues by members of the EglN (also called PHD) prolyl hydroxylase family. Deregulation of HIF, and particularly HIF2, drives the growth of VHL-defective ccRCCs. Drugs that inhibit the HIF-responsive gene product VEGF are now mainstays of ccRCC treatment. An allosteric HIF2 inhibitor was recently approved for the treatment of ccRCCs arising in the setting of VHL disease and has advanced to phase III testing for sporadic ccRCCs based on promising phase I/II data. Orally available EglN inhibitors are being tested for the treatment of anemia and ischemia. Five of these agents have been approved for the treatment of anemia in the setting of chronic kidney disease in various countries around the world.
William G. Kaelin Jr.
Tuberculosis (TB), caused by Mycobacterium tuberculosis infection, remains a leading cause of death from an infectious agent, resulting in more than a million deaths per year. Despite vaccines and chemotherapies, patients often harbor persister M. tuberculosis cells that resist immune assault and chemotherapeutic treatments, resulting in a latent TB infection (LTBI). In this issue of the JCI, Sharan et al. used an aerosol-based macaque model to show that weekly treatments with isoniazid and rifapentine for 3 months reduced active M. tuberculosis infection and LTBI. Lung tissue from treated animals showed fewer granulomas when compared with the untreated control animals. These findings suggest that it is possible to eliminate persister M. tuberculosis cells, thereby eliminating LTBI. If similar elimination routinely occurs in patients undergoing the isoniazid and rifapentine treatment, the hidden reservoir of M. tuberculosis associated with LTBI would be greatly reduced, allowing us to imagine, and eventually achieve, a world without TB.
William R. Jacobs Jr.
Patients with HPV-unrelated head and neck squamous cell carcinoma (HPV-unrelated HNSCC) show only modest benefit from treatment with PD-1 inhibitors (PD-1i). Targeting transforming growth factor β (TGF-β) may make PD-1i more effective by inducing T cell responses. In this issue of the JCI, Redman et al. performed a clinical trial in 14 patients with HPV-unrelated HNSCC using bintrafusp alfa, a bifunctional fusion protein that blocks PD-L1 and TGF-β. Primary tumors displayed pathologic responses with 5 of 14 patients having at least a partial response. While no primary tumor or metastatic lymph node demonstrated a complete pathologic response, the findings suggest that concurrent neoadjuvant inhibition of PD-L1 and TGF-β may provide a rational strategy to improve pathologic response and clinical outcome in patients with HPV-unrelated HNSCC.
R. Bryan Bell, Michael Gough, Marka Crittenden, Kristina Young
Chronic hepatitis B virus (HBV) infection remains a major global health problem. Hepatitis B surface antigen (HBsAg) loss has been accepted as the definition of a functional HBV cure. Recent studies found that while covalently closed circular DNA (cccDNA) is the predominant source of HBsAg in hepatitis B e antigen–positive (HBeAg-positive) patients, integrated HBV DNA (iDNA) is the main source in HBeAg-negative patients. Consequently, achieving a functional HBV cure will require not only silencing of cccDNA but also iDNA. Assays that distinguish the source of HBsAg are needed to evaluate emerging therapies. In this issue of the JCI, Grudda et al. developed a PCR-based assay that differentiated the source of HBsAg and explored the contributing sources of HBsAg in patients on nucleos(t)ide analog antivirals. These findings provide a tool for understanding the contribution of iDNA in HBV infection and may guide therapies toward a functional HBV cure.
Marc G. Ghany, Anna S. Lok
Global vaccination coverage remains indispensable in combatting the ongoing SARS-CoV-2 pandemic. Safety, efficacy, and durability of immune protection are the key parameters of randomized controlled trials (RCTs) and are essential for vaccine approvals, global distribution, and comprehensive population-vaccination programs. Immune protection from either vaccination or natural infection decreases over time, further challenged by rapid viral evolution. In this issue of the JCI, Sobieszczyk and colleagues report an update on the safety, efficacy, and durability of immune protection of AZD12222 in a large-scale, multinational, Phase III RCT. They report that protection lasted through 6 months, with immunity waning after 180 days. The study also highlights challenges facing vaccine trials, including the need for early unblinding for vulnerable participants, which may affect outcome measurements. Another challenge is to ensure fair representation of marginalized and minority ethnic groups in vaccine safety and efficacy studies worldwide.
Ranjeet Singh Mahla, Lynn B. Dustin
Sudden cardiac death (SCD) in patients with heart failure (HF) is allied with an imbalance in reduction and oxidation (redox) signaling in cardiomyocytes; however, the basic pathways and mechanisms governing redox homeostasis in cardiomyocytes are not fully understood. Here, we show that cytochrome b5 reductase 3 (CYB5R3), an enzyme known to regulate redox signaling in erythrocytes and vascular cells, is essential for cardiomyocyte function. Using a conditional cardiomyocyte-specific CYB5R3-knockout mouse, we discovered that deletion of CYB5R3 in male, but not female, adult cardiomyocytes causes cardiac hypertrophy, bradycardia, and SCD. The increase in SCD in CYB5R3-KO mice is associated with calcium mishandling, ventricular fibrillation, and cardiomyocyte hypertrophy. Molecular studies reveal that CYB5R3-KO hearts display decreased adenosine triphosphate (ATP), increased oxidative stress, suppressed coenzyme Q levels, and hemoprotein dysregulation. Finally, from a translational perspective, we reveal that the high-frequency missense genetic variant rs1800457, which translates into a CYB5R3 T117S partial loss-of-function protein, associates with decreased event-free survival (~20%) in Black persons with HF with reduced ejection fraction (HFrEF). Together, these studies reveal a crucial role for CYB5R3 in cardiomyocyte redox biology and identify a genetic biomarker for persons of African ancestry that may potentially increase the risk of death from HFrEF.
Nolan T. Carew, Heidi M. Schmidt, Shuai Yuan, Joseph C. Galley, Robert Hall, Helene M. Altmann, Scott A. Hahn, Megan P. Miller, Katherine C. Wood, Bethann Gabris, Margaret C. Stapleton, Sean Hartwick, Marco Fazzari, Yijen L. Wu, Mohamed Trebak, Brett A. Kaufman, Charles F. McTiernan, Francisco J. Schopfer, Placido Navas, Patrick H. Thibodeau, Dennis M. McNamara, Guy Salama, Adam C. Straub
Forkhead box O transcriptional factors, especially FoxO1 and FoxO3a, play critical roles in physiologic and pathologic immune responses. However, the function of FoxO4, another main member of the FoxO family, in lymphoid cells is still poorly understood. Here, we showed that loss of FoxO4 in T cells augmented IFN-γ production of Th1 cells in vitro. Correspondingly, conditional deletion of FoxO4 in CD4+ T cells enhanced T cell–specific responses to Listeria monocytogenes infection in vivo. Genome-wide occupancy and transcriptomic analyses identified Dkk3 (encoding the Dickkopf-3 protein) as a direct transcriptional target of FoxO4. Consistent with the FoxO4-DKK3 relationship, recombinant DKK3 protein restored normal levels of IFN-γ production in FoxO4-deficient Th1 cells through the downregulation of lymphoid enhancer–binding factor 1 (Lef1) expression. Together, our data suggest a potential FoxO4/DKK3 axis in Th1 cell differentiation, providing what we believe to be an important insight and supplement for FoxO family proteins in T lymphocyte biology and revealing a promising target for the treatment of immune-related diseases.
Xiang Chen, Jia Hu, Yunfei Wang, Younghee Lee, Xiaohong Zhao, Huiping Lu, Gengzhen Zhu, Hui Wang, Yu Jiang, Fan Liu, Yongzhen Chen, Byung-Seok Kim, Qinghua Zhou, Xindong Liu, Xiaohu Wang, Seon Hee Chang, Chen Dong
In addition to playing a major role in tumor cell biology, p53 generates a microenvironment that promotes antitumor immune surveillance via tumor-associated macrophages. We examined whether increasing p53 signaling in the tumor microenvironment influences antitumor T cell immunity. Our findings indicate that increased p53 signaling induced either pharmacologically with APR-246 (eprenetapopt) or in p53-overexpressing transgenic mice can disinhibit antitumor T cell immunity and augment the efficacy of immune checkpoint blockade. We demonstrated that increased p53 expression in tumor-associated macrophages induces canonical p53-associated functions such as senescence and activation of a p53-dependent senescence-associated secretory phenotype. This was linked with decreased expression of proteins associated with M2 polarization by tumor-associated macrophages. Our preclinical data led to the development of a clinical trial in patients with solid tumors combining APR-246 with pembrolizumab. Biospecimens from select patients participating in this ongoing trial showed that there was a suppression of M2-polarized myeloid cells and increase in T cell proliferation with therapy in those who responded to the therapy. Our findings, based on both genetic and a small molecule–based pharmacological approach, suggest that increasing p53 expression in tumor-associated macrophages reprograms the tumor microenvironment to augment the response to immune checkpoint blockade.
Arnab Ghosh, Judith Michels, Riccardo Mezzadra, Divya Venkatesh, Lauren Dong, Ricardo Gomez, Fadi Samaan, Yu-Jui Ho, Luis Felipe Campesato, Levi Mangarin, John Fak, Nathan Suek, Aliya Holland, Cailian Liu, Mohsen Abu-Akeel, Yonina Bykov, Hong Zhong, Kelly Fitzgerald, Sadna Budhu, Andrew Chow, Roberta Zappasodi, Katherine S. Panageas, Olivier de Henau, Marcus Ruscetti, Scott W. Lowe, Taha Merghoub, Jedd D. Wolchok
The vast majority of people with cystic fibrosis (CF) are now eligible for CF transmembrane regulator (CFTR) modulator therapy. The remaining individuals with CF harbor premature termination codons (PTCs) or rare CFTR variants with limited treatment options. Although the clinical modulator response can be reliably predicted using primary airway epithelial cells, primary cells carrying rare CFTR variants are scarce. To overcome this obstacle, cell lines can be created by overexpression of mouse Bmi-1 and human TERT (hTERT). Using this approach, we developed 2 non-CF and 6 CF airway epithelial cell lines, 3 of which were homozygous for the W1282X PTC variant. The Bmi-1/hTERT cell lines recapitulated primary cell morphology and ion transport function. The 2 F508del-CFTR cell lines responded robustly to CFTR modulators, which was mirrored in the parent primary cells and in the cell donors’ clinical response. Cereblon E3 ligase modulators targeting eukaryotic release factor 3a (eRF3a) rescued W1282X-CFTR function to approximately 20% of WT levels and, when paired with G418, rescued G542X-CFTR function to approximately 50% of WT levels. Intriguingly, eRF3a degraders also diminished epithelial sodium channel (ENaC) function. These studies demonstrate that Bmi-1/hTERT cell lines faithfully mirrored primary cell responses to CFTR modulators and illustrate a therapeutic approach to rescue CFTR nonsense mutations.
Rhianna E. Lee, Catherine A. Lewis, Lihua He, Emily C. Bulik-Sullivan, Samuel C. Gallant, Teresa M. Mascenik, Hong Dang, Deborah M. Cholon, Martina Gentzsch, Lisa C. Morton, John T. Minges, Jonathan W. Theile, Neil A. Castle, Michael R. Knowles, Adam J. Kimple, Scott H. Randell
BACKGROUND Several molecular imaging strategies can identify bacterial infections in humans. PET affords the potential for sensitive infection detection deep within the body. Among PET-based approaches, antibiotic-based radiotracers, which often target key bacterial-specific enzymes, have considerable promise. One question for antibiotic radiotracers is whether antimicrobial resistance (AMR) reduces specific accumulation within bacteria, diminishing the predictive value of the diagnostic test.METHODS Using a PET radiotracer based on the antibiotic trimethoprim (TMP), [11C]-TMP, we performed in vitro uptake studies in susceptible and drug-resistant bacterial strains and whole-genome sequencing (WGS) in selected strains to identify TMP resistance mechanisms. Next, we queried the NCBI database of annotated bacterial genomes for WT and resistant dihydrofolate reductase (DHFR) genes. Finally, we initiated a first-in-human protocol of [11C]-TMP in patients infected with both TMP-sensitive and TMP-resistant organisms to demonstrate the clinical feasibility of the tool.RESULTS We observed robust [11C]-TMP uptake in our panel of TMP-sensitive and -resistant bacteria, noting relatively variable and decreased uptake in a few strains of P. aeruginosa and E. coli. WGS showed that the vast majority of clinically relevant bacteria harbor a WT copy of DHFR, targetable by [11C]-TMP, and that despite the AMR, these strains should be “imageable.” Clinical imaging of patients with [11C]-TMP demonstrated focal radiotracer uptake in areas of infectious lesions.CONCLUSION This work highlights an approach to imaging bacterial infection in patients, which could affect our understanding of bacterial pathogenesis as well as our ability to better diagnose infections and monitor response to therapy.TRIAL REGISTRATION ClinicalTrials.gov NCT03424525.FUNDING Institute for Translational Medicine and Therapeutics, Burroughs Wellcome Fund, NIH Office of the Director Early Independence Award (DP5-OD26386), and University of Pennsylvania NIH T32 Radiology Research Training Grant (5T32EB004311-12).
Iris K. Lee, Daniel A. Jacome, Joshua K. Cho, Vincent Tu, Anthony J. Young, Tiffany Dominguez, Justin D. Northrup, Jean M. Etersque, Hsiaoju S. Lee, Andrew Ruff, Ouniol Aklilu, Kyle Bittinger, Laurel J. Glaser, Daniel Dorgan, Denis Hadjiliadis, Rahul M. Kohli, Robert H. Mach, David A. Mankoff, Robert K. Doot, Mark A. Sellmyer
Osteolytic bone disease is a hallmark of multiple myeloma (MM). A significant fraction (~20%) of MM patients do not develop osteolytic lesions (OLs). The molecular basis for the absence of bone disease in MM is not understood. We combined PET-CT and gene expression profiling (GEP) of purified BM CD138+ MM cells from 512 newly diagnosed MM patients to reveal that elevated expression of cystatin M/E (CST6) was significantly associated with the absence of OL in MM. An enzyme-linked immunosorbent assay revealed a strong correlation between CST6 levels in BM serum/plasma and CST6 mRNA expression. Both recombinant CST6 protein and BM serum from patients with high CST6 significantly inhibited the activity of the osteoclast-specific protease cathepsin K and blocked osteoclast differentiation and function. Recombinant CST6 inhibited bone destruction in ex vivo and in vivo myeloma models. Single-cell RNA-Seq showed that CST6 attenuates polarization of monocytes to osteoclast precursors. Furthermore, CST6 protein blocks osteoclast differentiation by suppressing cathepsin-mediated cleavage of NF-κB/p100 and TRAF3 following RANKL stimulation. Secretion by MM cells of CST6, an inhibitor of osteoclast differentiation and function, suppresses osteolytic bone disease in MM and probably other diseases associated with osteoclast-mediated bone loss.
Dongzheng Gai, Jin-Ran Chen, James P. Stewart, Intawat Nookaew, Hasem Habelhah, Cody Ashby, Fumou Sun, Yan Cheng, Can Li, Hongwei Xu, Bailu Peng, Tarun K. Garg, Carolina Schinke, Sharmilan Thanendrarajan, Maurizio Zangari, Fangping Chen, Bart Barlogie, Frits van Rhee, Guido Tricot, John D. Shaughnessy Jr., Fenghuang Zhan
Background We report updated safety, efficacy, and immunogenicity of AZD1222 (ChAdOx1 nCoV-19) from an ongoing phase 3 trial.Methods Adults at increased risk of SARS-CoV-2 infection were randomized (2:1), stratified by age, to receive 2 doses of AZD1222 or placebo. The primary efficacy end point was confirmed SARS-CoV-2 reverse-transcriptase PCR–positive (RT-PCR–positive) symptomatic COVID-19 at 15 or more days after a second dose in baseline SARS-CoV-2–seronegative participants. The 21,634 and 10,816 participants were randomized to AZD1222 and placebo, respectively.Findings Data cutoff for this analysis was July 30, 2021; median follow-up from second dose was 78 and 71 days for the double-blind period (censoring at unblinding or nonstudy COVID-19 vaccination) and 201 and 82 days for the period to nonstudy COVID-19 vaccination (regardless of unblinding) in the AZD1222 and placebo groups, respectively. For the primary efficacy end point in the double-blind period (141 and 184 events; incidence rates: 39.2 and 118.8 per 1,000 person years), vaccine efficacy was 67.0% (P < 0.001). In the period to nonstudy COVID-19 vaccination, incidence of events remained consistently low and stable through 6 months in the AZD1222 group; for the primary efficacy end point (328 and 219 events; incidence rates: 36.4, 108.4) and severe/critical disease (5 and 13 events; incidence rates: 0.6, 6.4), respective vaccine efficacy estimates were 65.1% and 92.1%. AZD1222 elicited humoral immune responses over time, with waning at day 180. No emergent safety issues were seen.Conclusion AZD1222 is safe and well tolerated, demonstrating durable protection and immunogenicity with median follow-up (AZD1222 group) of 6 months.Trial registration ClinicalTrials.gov NCT04516746.Funding AstraZeneca; US government.
Magdalena E. Sobieszczyk, Jill Maaske, Ann R. Falsey, Stephanie Sproule, Merlin L. Robb, Robert W. Frenck Jr., Hong-Van Tieu, Kenneth H. Mayer, Lawrence Corey, Kathleen M. Neuzil, Tina Tong, Margaret Brewinski Isaacs, Holly Janes, Himanshu Bansal, Lindsay M. Edwards, Justin A. Green, Elizabeth J. Kelly, Kathryn Shoemaker, Therese Takas, Tom White, Prakash Bhuyan, Tonya Villafana, and Ian Hirsch, on behalf of the AstraZeneca AZD1222 Clinical Study Group
Background Herpes simplex virus lymphadenitis (HSVL) is an unusual presentation of HSV reactivation in patients with chronic lymphocytic leukemia (CLL) and is characterized by systemic symptoms and no herpetic lesions. The immune responses during HSVL have not, to our knowledge, been studied.Methods Peripheral blood and lymph node (LN) samples were obtained from a patient with HSVL. HSV-2 viral load, antibody levels, B and T cell responses, cytokine levels, and tumor burden were measured.Results The patient showed HSV-2 viremia for at least 6 weeks. During this period, she had a robust HSV-specific antibody response with neutralizing and antibody-dependent cellular phagocytotic activity. Activated (HLA-DR+, CD38+) CD4+ and CD8+ T cells increased 18-fold, and HSV-specific CD8+ T cells in the blood were detected at higher numbers. HSV-specific B and T cell responses were also detected in the LN. Markedly elevated levels of proinflammatory cytokines in the blood were also observed. Surprisingly, a sustained decrease in CLL tumor burden without CLL-directed therapy was observed with this and also a prior episode of HSVL.Conclusion HSVL should be considered part of the differential diagnosis in patients with CLL who present with signs and symptoms of aggressive lymphoma transformation. An interesting finding was the sustained tumor control after 2 episodes of HSVL in this patient. A possible explanation for the reduction in tumor burden may be that the HSV-specific response served as an adjuvant for the activation of tumor-specific or bystander T cells. Studies in additional patients with CLL are needed to confirm and extend these findings.Funding NIH grants 4T32CA160040, UL1TR002378, and 5U19AI057266 and NIH contracts 75N93019C00063 and HHSN261200800001E. Neil W. and William S. Elkin Fellowship (Winship Cancer Institute).
Andres Chang, Anton M. Sholukh, Andreas Wieland, David L. Jaye, Mary Carrington, Meei-Li Huang, Hong Xie, Keith R. Jerome, Pavitra Roychoudhury, Alexander L. Greninger, Jean L. Koff, Jonathon B. Cohen, David M. Koelle, Lawrence Corey, Christopher R. Flowers, Rafi Ahmed
BACKGROUND Head and neck squamous cell carcinoma not associated with HPV (HPV-unrelated HNSCC) is associated with a high rate of recurrence and poor survival.METHODS We conducted a clinical trial in 14 patients with newly diagnosed HPV-unrelated HNSCC to evaluate the safety and efficacy of neoadjuvant bintrafusp alfa, a bifunctional fusion protein that blocks programmed death ligand 1 (PD-L1) and neutralizes TGF-β.RESULTS Bintrafusp alfa was well tolerated, and no treatment-associated surgical delays or complications occurred. Objective pathologic responses (PRs) were observed, and 12 of the 14 (86%) patients were alive and disease free at 1 year. Alterations in Treg infiltration and spatial distribution relative to proliferating CD8+ T cells indicated a reversal of Treg immunosuppression in the primary tumor. Detection of neoepitope-specific tumor T cell responses, but not virus-specific responses, correlated with the development of a PR. Detection of neoepitope-specific responses and PRs in tumors was not correlated with genomic features or tumor antigenicity but was associated with reduced pretreatment myeloid cell tumor infiltration. These results indicate that dual PD-L1 and TGF-β blockade can safely enhance tumor antigen–specific immunity and highlight the feasibility of multimechanism neoadjuvant immunotherapy for patients with HPV-unrelated HNSCC.CONCLUSION Our studies provide insight into the ability of neoadjuvant immunotherapy to induce polyclonal neoadjuvant–specific T cell responses in tumors and suggest that features of the tumor microenvironment, such as myeloid cell infiltration, may be a major determinant of enhanced antitumor immunity following such treatment.TRIAL REGISTRATION ClinicalTrials.gov NCT04247282.FUNDING This work was funded by the Center for Cancer Research, the NCI, and the Intramural Research Program of the NIDCD, NIH. Bintrafusp alfa was provided by the health care business of Merck KGaA (Darmstadt, Germany), through a Cooperative Research and Development Agreement with the NCI. Additional funding was provided by ImmunityBio through a Cooperative Research and Development Agreement with the NIDCD.
Jason M. Redman, Jay Friedman, Yvette Robbins, Cem Sievers, Xinping Yang, Wiem Lassoued, Andrew Sinkoe, Antonios Papanicolau-Sengos, Chyi-Chia Lee, Jennifer L. Marte, Evrim Turkbey, Wojtek Mydlarz, Arjun Joshi, Nyall R. London Jr., Matthew Pierce, Rodney Taylor, Steven Hong, Andy Nguyen, Patrick Soon-Shiong, Jeffrey Schlom, James L. Gulley, Clint T. Allen
A once-weekly oral dose of isoniazid and rifapentine for 3 months (3HP) is recommended by the CDC for treatment of latent tuberculosis infection (LTBI). The aim of this study is to assess 3HP-mediated clearance of M. tuberculosis bacteria in macaques with asymptomatic LTBI. Twelve Indian-origin rhesus macaques were infected with a low dose (~10 CFU) of M. tuberculosis CDC1551 via aerosol. Six animals were treated with 3HP and 6 were left untreated. The animals were imaged via PET/CT at frequent intervals. Upon treatment completion, all animals except 1 were coinfected with SIV to assess reactivation of LTBI to active tuberculosis (ATB). Four of 6 treated macaques showed no evidence of persistent bacilli or extrapulmonary spread until the study end point. PET/CT demonstrated the presence of significantly more granulomas in untreated animals relative to the treated group. The untreated animals harbored persistent bacilli and demonstrated tuberculosis (TB) reactivation following SIV coinfection, while none of the treated animals reactivated to ATB. 3HP treatment effectively reduced persistent infection with M. tuberculosis and prevented reactivation of TB in latently infected macaques.
Riti Sharan, Shashank R. Ganatra, Dhiraj K. Singh, Journey Cole, Taylor W. Foreman, Rajesh Thippeshappa, Charles A. Peloquin, Vinay Shivanna, Olga Gonzalez, Cheryl L. Day, Neel R. Gandhi, Edward J. Dick Jr., Shannan Hall-Ursone, Smriti Mehra, Larry S. Schlesinger, Jyothi Rengarajan, Deepak Kaushal
The focus of hepatitis B functional cure, defined as sustained loss of hepatitis B virus (HBV) surface antigen (HBsAg) and HBV DNA from blood, is on eliminating or silencing the intranuclear template for HBV replication, covalently closed circular DNA (cccDNA). However, HBsAg also derives from HBV DNA integrated into the host genome (iDNA). Little is known about the contribution of iDNA to circulating HBsAg with current therapeutics. We applied a multiplex droplet digital PCR assay to demonstrate that iDNA is responsible for maintaining HBsAg quantities in some individuals. Using paired bulk liver tissue from 16 HIV/HBV-coinfected persons on nucleos(t)ide analog (NUC) therapy, we demonstrate that people with larger HBsAg declines between biopsies derive HBsAg from cccDNA, whereas people with stable HBsAg levels derive predominantly from iDNA. We applied our assay to individual hepatocytes in paired tissues from 3 people and demonstrated that the individual with significant HBsAg decline had a commensurate loss of infected cells with transcriptionally active cccDNA, while individuals without HBsAg decline had stable or increasing numbers of cells producing HBsAg from iDNA. We demonstrate that while NUC therapy may be effective at controlling cccDNA replication and transcription, innovative treatments are required to address iDNA transcription that sustains HBsAg production.
Tanner Grudda, Hyon S. Hwang, Maraake Taddese, Jeffrey Quinn, Mark S. Sulkowski, Richard K. Sterling, Ashwin Balagopal, Chloe L. Thio
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects motor neurons. Mutations in the SPTLC1 subunit of serine palmitoyltransferase (SPT), which catalyzes the first step in the de novo synthesis of sphingolipids (SLs), cause childhood-onset ALS. SPTLC1-ALS variants map to a transmembrane domain that interacts with ORMDL proteins, negative regulators of SPT activity. We show that ORMDL binding to the holoenzyme complex is impaired in cells expressing pathogenic SPTLC1-ALS alleles, resulting in increased SL synthesis and a distinct lipid signature. C-terminal SPTLC1 variants cause peripheral hereditary sensory and autonomic neuropathy type 1 (HSAN1) due to the synthesis of 1-deoxysphingolipids (1-deoxySLs) that form when SPT metabolizes L-alanine instead of L-serine. Limiting L-serine availability in SPTLC1-ALS–expressing cells increased 1-deoxySL and shifted the SL profile from an ALS to an HSAN1-like signature. This effect was corroborated in an SPTLC1-ALS pedigree in which the index patient uniquely presented with an HSAN1 phenotype, increased 1-deoxySL levels, and an L-serine deficiency. These data demonstrate how pathogenic variants in different domains of SPTLC1 give rise to distinct clinical presentations that are nonetheless modifiable by substrate availability.
Museer A. Lone, Mari J. Aaltonen, Aliza Zidell, Helio F. Pedro, Jonas A. Morales Saute, Shalett Mathew, Payam Mohassel, Carsten G. Bönnemann, Eric A. Shoubridge, Thorsten Hornemann