Issue published August 15, 2022 Previous issue | Next issue
- Volume 132, Issue 16
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On the cover: PD-1 signaling in aged kidneys and diseased podocytes
Pippin et al. report that the PD-1 pathway contributes to aging of the kidney and demonstrate that treating mice with anti–PD-1 antibody improves the aging phenotype. Image credit: Juan Gaertner/Shutterstock.
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Review Series
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Abstract
Over the course of a human lifespan, genome integrity erodes, leading to an increased abundance of several types of chromatin changes. The abundance of DNA lesions (chemical perturbations to nucleotides) increases with age, as does the number of genomic mutations and transcriptional disruptions caused by replication or transcription of those lesions, respectively. At the epigenetic level, precise DNA methylation patterns degrade, likely causing increasingly stochastic variations in gene expression. Similarly, the tight regulation of histone modifications begins to unravel. The genomic instability caused by these mechanisms allows transposon element reactivation and remobilization, further mutations, gene dysregulation, and cytoplasmic chromatin fragments. This cumulative genomic instability promotes cell signaling events that drive cell fate decisions and extracellular communications known to disrupt tissue homeostasis and regeneration. In this Review, we focus on age-related epigenetic changes and their interactions with age-related genomic changes that instigate these events.
Authors
Carolina Soto-Palma, Laura J. Niedernhofer, Christopher D. Faulk, Xiao Dong
×Abstract
Aging and metabolism are inextricably linked, and many age-related changes in body composition, including increased central adiposity and sarcopenia, have underpinnings in fundamental aging processes. These age-related changes are further exacerbated by a sedentary lifestyle and can be in part prevented by maintenance of activity with aging. Here we explore the age-related changes seen in individual metabolic tissues — adipose, muscle, and liver — as well as globally in older adults. We also discuss the available evidence for therapeutic interventions such as caloric restriction, resistance training, and senolytic and senomorphic drugs to maintain healthy metabolism with aging, focusing on data from human studies.
Authors
Allyson K. Palmer, Michael D. Jensen
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Commentaries
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Abstract
Multiple cancer types demonstrate abnormal expression of repetitive RNA sequences as a form of epigenetic instability. There is growing interest in understanding the role of repetitive RNAs in cancer pathogenesis and immunogenicity and in their potential role as diagnostic or therapeutic biomarkers. In this issue of the JCI, Porter and colleagues report on satellite RNA in a subset of ovarian cancers. The authors found that high expression of human satellite (HSAT) repeats — but not other families of repeats — was associated with an immunosuppressive phenotype in ovarian cancer cell lines and tumor samples. Further induction of HSAT RNA levels in vitro, surprisingly, leads to innate immune activation, suggesting a potential therapeutic strategy. This work highlights the expanding role of repetitive RNAs in tumor biology and the need to better define specific classes of repetitive elements expressed in cancer — as well as their role in tumorigenesis, tumor immunity, and the host response to cancer.
Authors
Shridar Ganesan
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Autoimmunity has long been regarded as the polar opposite of immunodeficiency, but clinical and experimental evidence refute this notion. Indeed, numerous inborn or acquired immunodeficiency syndromes are characterized by the development of autoimmune complications in the setting of deficient immune defenses against microbial pathogens. Appreciation that much of the daily business of a healthy immune system is the avoidance of potentially harmful responses to innocuous environmental antigens or components of the host organism helps provide a context for these observations. In this issue of the JCI, Abt and colleagues report on purine nucleoside phosphorylase (PNP) deficiency, exploring the basis for the autoimmune complications that develop in this particular form of T cell immune deficiency and assigning a key role for overactivation of TLR7.
Authors
David A. Fox
×Abstract
Chimeric antigen receptor (CAR) T cells have demonstrated success in treating select hematological malignancies, but their activity in solid tumors has been comparably modest. Challenges specific to treating solid tumors include trafficking and distribution throughout the tumor site, overcoming the immunosuppressive tumor microenvironment (TME), and identifying antigenic targets that are widely expressed and indispensable to tumor biology. In this issue of the JCI, Tian et al. describe the use of bicistronic CAR T cells that target multiple antigens expressed in neuroblastoma to overcome antigenic heterogeneity. Combining this approach with interventions that enhance T cell trafficking and prevent acquired dysfunction in the TME may lead to a long-awaited breakthrough in the clinical implementation of CAR T cells for the treatment of solid tumors.
Authors
Ayush Pant, Christopher M. Jackson
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Understanding the loss of kidney function resulting from kidney aging has become an emerging research focus that will facilitate the future development of antisenolytic treatments. In this issue of the JCI, Pippin et al. first identified PD-1 upregulation in the aged mouse podocyte via unbiased RNA-seq analysis. Overexpression of PD-1 in immortalized mouse podocytes induced cell death and a senescence-associated secretory phenotype, suggesting the pathological role of PD-1 upregulation in aged podocytes. Blocking PD-1 signaling via a neutralizing anti-PD-1 antibody reversed the aged phenotype in the aged mice and ameliorated proteinuria in an experimental focal segmental glomerulosclerosis (FSGS) mouse model. These findings highlight the role of PD-1 signaling in kidney aging and its therapeutic potential for human clinical trials.
Authors
Samuel Mon-Wei Yu, John Cijiang He
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Research Articles
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Abstract
Targeted protein degradation is a rapidly advancing and expanding therapeutic approach. Drugs that degrade GSPT1 via the CRL4CRBN ubiquitin ligase are a new class of cancer therapy in active clinical development with evidence of activity against acute myeloid leukemia in early-phase trials. However, other than activation of the integrated stress response, the downstream effects of GSPT1 degradation leading to cell death are largely undefined, and no murine models are available to study these agents. We identified the domains of GSPT1 essential for cell survival and show that GSPT1 degradation leads to impaired translation termination, activation of the integrated stress response pathway, and TP53-independent cell death. CRISPR/Cas9 screens implicated decreased translation initiation as protective following GSPT1 degradation, suggesting that cells with higher levels of translation are more susceptible to the effects of GSPT1 degradation. We defined 2 Crbn amino acids that prevent Gspt1 degradation in mice, generated a knockin mouse with alteration of these residues, and demonstrated the efficacy of GSPT1-degrading drugs in vivo with relative sparing of numbers and function of long-term hematopoietic stem cells. Our results provide a mechanistic basis for the use of GSPT1 degraders for the treatment of cancer, including TP53-mutant acute myeloid leukemia.
Authors
Rob S. Sellar, Adam S. Sperling, Mikołaj Słabicki, Jessica A. Gasser, Marie E. McConkey, Katherine A. Donovan, Nada Mageed, Dylan N. Adams, Charles Zou, Peter G. Miller, Ravi K. Dutta, Steffen Boettcher, Amy E. Lin, Brittany Sandoval, Vanessa A. Quevedo Barrios, Veronica Kovalcik, Jonas Koeppel, Elizabeth K. Henderson, Emma C. Fink, Lu Yang, Anthony Chan, Sheela Pangeni Pokharel, Erik J. Bergstrom, Rajan Burt, Namrata D. Udeshi, Steven A. Carr, Eric S. Fischer, Chun-Wei Chen, Benjamin L. Ebert
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Plasmacytoid dendritic cells (pDCs) are a professional type I IFN producer that play critical roles in the pathogenesis of autoimmune diseases. However, both genetic regulation of the function of pDCs and their relationships with autoimmunity are largely undetermined. Here, we investigated the causality of the neutrophil cytosolic factor 1 (NCF1) missense variant, which is one of the most significant associated risk variants for lupus, and found that the substitution of arginine (R) for histidine (H) at position 90 in the NCF1 protein (NCF1 p.R90H) led to excessive activation of pDCs. A mechanism study demonstrated that p.R90H reduced the affinity of NCF1 for phospholipids, thereby impairing endosomal localization of NCF1. As NCF1 is a subunit of the NADPH oxidase 2 (NOX2) complex, this impairment led to an acidified endosomal pH and facilitated downstream TLR signaling. Consistently, the homozygous knockin mice manifested aggravated lupus progression in a pDC-dependent lupus model. More important, pharmaceutical intervention revealed that hydroxychloroquine (HCQ) could antagonize the detrimental function of NCF1 p.R90H in the lupus model and systemic lupus erythematosus samples, supporting the idea that NCF1 p.R90H could be identified as a genetic biomarker for HCQ application. Therefore, our study provides insights into the genetic control of pDC function and a paradigm for applying genetic variants to improve targeted therapy for autoimmune diseases.
Authors
Yao Meng, Jianyang Ma, Chao Yao, Zhizhong Ye, Huihua Ding, Can Liu, Jun Li, Guanhua Li, Yuke He, Jia Li, Zhihua Yin, Li Wu, Haibo Zhou, Nan Shen
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Chimeric antigen receptor (CAR) T cell therapies targeting single antigens have performed poorly in clinical trials for solid tumors due to heterogenous expression of tumor-associated antigens (TAAs), limited T cell persistence, and T cell exhaustion. Here, we aimed to identify optimal CARs against glypican 2 (GPC2) or CD276 (B7-H3), which were highly but heterogeneously expressed in neuroblastoma (NB), a lethal extracranial solid tumor of childhood. First, we examined CAR T cell expansion in the presence of targets by digital droplet PCR. Next, using pooled competitive optimization of CAR by cellular indexing of transcriptomes and epitopes by sequencing (CITE-Seq), termed P-COCC, we simultaneously analyzed protein and transcriptome expression of CAR T cells to identify high-activity CARs. Finally, we performed cytotoxicity assays to identify the most effective CAR against each target and combined the CARs into a bicistronic “OR” CAR (BiCisCAR). BiCisCAR T cells effectively eliminated tumor cells expressing GPC2 or CD276. Furthermore, the BiCisCAR T cells demonstrated prolonged persistence and resistance to exhaustion when compared with CARs targeting a single antigen. This study illustrated that targeting multiple TAAs with BiCisCAR may overcome heterogenous expression of target antigens in solid tumors and identified a potent, clinically relevant CAR against NB. Moreover, our multimodal approach integrating competitive expansion, P-COCC, and cytotoxicity assays is an effective strategy to identify potent CARs among a pool of candidates.
Authors
Meijie Tian, Adam T. Cheuk, Jun S. Wei, Abdalla Abdelmaksoud, Hsien-Chao Chou, David Milewski, Michael C. Kelly, Young K. Song, Christopher M. Dower, Nan Li, Haiying Qin, Yong Yean Kim, Jerry T. Wu, Xinyu Wen, Mehdi Benzaoui, Katherine E. Masih, Xiaolin Wu, Zhongmei Zhang, Sherif Badr, Naomi Taylor, Brad St. Croix, Mitchell Ho, Javed Khan
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Aberrant expression of viral-like repeat elements is a common feature of epithelial cancers, and the substantial diversity of repeat species provides a distinct view of the cancer transcriptome. Repeatome profiling across ovarian, pancreatic, and colorectal cell lines identifies distinct clustering independent of tissue origin that is seen with coding gene analysis. Deeper analysis of ovarian cancer cell lines demonstrated that human satellite II (HSATII) satellite repeat expression was highly associated with epithelial-mesenchymal transition (EMT) and anticorrelated with IFN-response genes indicative of a more aggressive phenotype. SATII expression — and its correlation with EMT and anticorrelation with IFN-response genes — was also found in ovarian cancer RNA-Seq data and was associated with significantly shorter survival in a second independent cohort of patients with ovarian cancer. Repeat RNAs were enriched in tumor-derived extracellular vesicles capable of stimulating monocyte-derived macrophages, demonstrating a mechanism that alters the tumor microenvironment with these viral-like sequences. Targeting of HSATII with antisense locked nucleic acids stimulated IFN response and induced MHC I expression in ovarian cancer cell lines, highlighting a potential strategy of modulating the repeatome to reestablish antitumor cell immune surveillance.
Authors
Rebecca L. Porter, Siyu Sun, Micayla N. Flores, Emily Berzolla, Eunae You, Ildiko E. Phillips, Neelima KC, Niyati Desai, Eric C. Tai, Annamaria Szabolcs, Evan R. Lang, Amaya Pankaj, Michael J. Raabe, Vishal Thapar, Katherine H. Xu, Linda T. Nieman, Daniel C. Rabe, David L. Kolin, Elizabeth H. Stover, David Pepin, Shannon L. Stott, Vikram Deshpande, Joyce F. Liu, Alexander Solovyov, Ursula A. Matulonis, Benjamin D. Greenbaum, David T. Ting
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With an aging population, kidney health becomes an important medical and socioeconomic factor. Kidney aging mechanisms are not well understood. We previously showed that podocytes isolated from aged mice exhibit increased expression of programmed cell death protein 1 (PD-1) surface receptor and its 2 ligands (PD-L1 and PD-L2). PDCD1 transcript increased with age in microdissected human glomeruli, which correlated with lower estimated glomerular filtration rate and higher segmental glomerulosclerosis and vascular arterial intima-to-lumen ratio. In vitro studies in podocytes demonstrated a critical role for PD-1 signaling in cell survival and in the induction of a senescence-associated secretory phenotype. To prove PD-1 signaling was critical to podocyte aging, aged mice were injected with anti–PD-1 antibody. Treatment significantly improved the aging phenotype in both kidney and liver. In the glomerulus, it increased the life span of podocytes, but not that of parietal epithelial, mesangial, or endothelial cells. Transcriptomic and immunohistochemistry studies demonstrated that anti–PD-1 antibody treatment improved the health span of podocytes. Administering the same anti–PD-1 antibody to young mice with experimental focal segmental glomerulosclerosis (FSGS) lowered proteinuria and improved podocyte number. These results suggest a critical contribution of increased PD-1 signaling toward both kidney and liver aging and in FSGS.
Authors
Jeffrey W. Pippin, Natalya Kaverina, Yuliang Wang, Diana G. Eng, Yuting Zeng, Uyen Tran, Carol J. Loretz, Anthony Chang, Shreeram Akilesh, Chetan Poudel, Hannah S. Perry, Christopher O’Connor, Joshua C. Vaughan, Markus Bitzer, Oliver Wessely, Stuart J. Shankland
×Abstract
Human cytomegalovirus (HCMV) is the most common congenital infection and a leading cause of stillbirth, neurodevelopmental impairment, and pediatric hearing loss worldwide. Development of a maternal vaccine or therapeutic to prevent congenital HCMV has been hindered by limited knowledge of the immune responses that protect against HCMV transmission in utero. To identify protective antibody responses, we measured HCMV-specific IgG binding and antiviral functions in paired maternal and cord blood sera from HCMV-seropositive transmitting (n = 41) and non-transmitting (n = 40) mother-infant dyads identified via a large, US-based, public cord blood bank. We found that high-avidity IgG binding to HCMV and antibody-dependent cellular phagocytosis (ADCP) were associated with reduced risk of congenital HCMV infection. We also determined that HCMV-specific IgG activation of FcγRI and FcγRII was enhanced in non-transmitting dyads and that increased ADCP responses were mediated through both FcγRI and FcγRIIA expressed on human monocytes. These findings suggest that engagement of FcγRI/FcγRIIA and Fc effector functions including ADCP may protect against congenital HCMV infection. Taken together, these data can guide future prospective studies on immune correlates against congenital HCMV transmission and inform HCMV vaccine and immunotherapeutic development.
Authors
Eleanor C. Semmes, Itzayana G. Miller, Courtney E. Wimberly, Caroline T. Phan, Jennifer A. Jenks, Melissa J. Harnois, Stella J. Berendam, Helen Webster, Jillian H. Hurst, Joanne Kurtzberg, Genevieve G. Fouda, Kyle M. Walsh, Sallie R. Permar
×Abstract
Purine nucleoside phosphorylase (PNP) enables the breakdown and recycling of guanine nucleosides. PNP insufficiency in humans is paradoxically associated with both immunodeficiency and autoimmunity, but the mechanistic basis for these outcomes is incompletely understood. Here, we identify two immune lineage-dependent consequences of PNP inactivation dictated by distinct gene interactions. During T cell development, PNP inactivation is synthetically lethal with downregulation of the dNTP triphosphohydrolase SAMHD1. This interaction requires deoxycytidine kinase activity and is antagonized by microenvironmental deoxycytidine. In B lymphocytes and macrophages, PNP regulates Toll-like receptor 7 signaling by controlling the levels of its (deoxy)guanosine nucleoside ligands. Overriding this regulatory mechanism promotes germinal center formation in the absence of exogenous antigen and accelerates disease in a mouse model of autoimmunity. This work reveals that one purine metabolism gene protects against immunodeficiency and autoimmunity via independent mechanisms operating in distinct immune lineages and identifies PNP as a potentially novel metabolic immune checkpoint.
Authors
Evan R. Abt, Khalid Rashid, Thuc M. Le, Suwen Li, Hailey R. Lee, Vincent Lok, Luyi Li, Amanda L. Creech, Amanda N. Labora, Hanna K. Mandl, Alex K. Lam, Arthur Cho, Valerie Rezek, Nanping Wu, Gabriel Abril-Rodriguez, Ethan W. Rosser, Steven D. Mittelman, Willy Hugo, Thomas Mehrling, Shanta Bantia, Antoni Ribas, Timothy R. Donahue, Gay M. Crooks, Ting-Ting Wu, Caius G. Radu
×Abstract
Accurately identifying patients who respond to immunotherapy remains clinically challenging. A noninvasive method that can longitudinally capture information about immune cell function and assist in the early assessment of tumor responses is highly desirable for precision immunotherapy. Here, we show that PET imaging using a granzyme B–targeted radiotracer named 68Ga-grazytracer, could noninvasively and effectively predict tumor responses to immune checkpoint inhibitors and adoptive T cell transfer therapy in multiple tumor models. 68Ga-grazytracer was designed and selected from several radiotracers based on non-aldehyde peptidomimetics, and exhibited excellent in vivo metabolic stability and favorable targeting efficiency to granzyme B secreted by effector CD8+ T cells during immune responses. 68Ga-grazytracer permitted more sensitive discrimination of responders and nonresponders than did 18F-fluorodeoxyglucose, distinguishing between tumor pseudoprogression and true progression upon immune checkpoint blockade therapy in mouse models with varying immunogenicity. In a preliminary clinical trial with 5 patients, no adverse events were observed after 68Ga-grazytracer injection, and clinical responses in cancer patients undergoing immunotherapy were favorably correlated with 68Ga-grazytracer PET results. These results highlight the potential of 68Ga-grazytracer PET to enhance the clinical effectiveness of granzyme B secretion–related immunotherapies by supporting early response assessment and precise patient stratification in a noninvasive and longitudinal manner.
Authors
Haoyi Zhou, Yanpu Wang, Hongchuang Xu, Xiuling Shen, Ting Zhang, Xin Zhou, Yuwen Zeng, Kui Li, Li Zhang, Hua Zhu, Xing Yang, Nan Li, Zhi Yang, Zhaofei Liu
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)