Issue published August 1, 2019 Previous issue | Next issue
- Volume 129, Issue 8
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On the cover: Targeting mitochondrial cardiolipin in diabetic kidney disease
In this issue of the JCI, Ducasa et al. interrogated the role of the cholesterol and phospholipid transporter ABCA1 in podocyte injury in diabetic kidney disease (DKD), focusing on its contribution to aberrant mitochondrial metabolism. Whereas podocyte-specific ABCA1 deficiency increased mitochondrial cardiolipin and impaired oxidative phosphorylation, inducing ABCA1 expression or stabilizing cardiolipin reduced podocyte injury and improved DKD-like pathology in mouse models. Altogether, these insights reveal potential therapeutic targets for managing DKD progression. The cover image features a transmission electron microscopy image highlighting the presence of mitochondria in podocyte foot processes within the glomerular filtration barrier. Image credit: Hazel Szeto and Shaoyi Liu.
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Review Series
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Abstract
Skin and intestinal epithelial barriers play a pivotal role in protecting underlying tissues from harsh external environments. The protective role of these epithelia is, in part, dependent on a remarkable capacity to restore barrier function and tissue homeostasis after injury. In response to damage, epithelial wounds repair by a series of events that integrate epithelial responses with those of resident and infiltrating immune cells including neutrophils and monocytes/macrophages. Compromise of this complex interplay predisposes to development of chronic nonhealing wounds, contributing to morbidity and mortality of many diseases. Improved understanding of crosstalk between epithelial and immune cells during wound repair is necessary for development of better pro-resolving strategies to treat debilitating complications of disorders ranging from inflammatory bowel disease to diabetes. In this Review we focus on epithelial and innate immune cell interactions that mediate wound healing and restoration of tissue homeostasis in the skin and intestine.
Authors
Jennifer C. Brazil, Miguel Quiros, Asma Nusrat, Charles A. Parkos
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Immune cells are pivotal in the reaction to injury, whereupon, under ideal conditions, repair and resolution phases restore homeostasis following initial acute inflammation. Immune cell activation and reprogramming require transcriptional changes that can only be initiated if epigenetic alterations occur. Recently, accelerated deciphering of epigenetic mechanisms has extended knowledge of epigenetic regulation, including long-distance chromatin remodeling, DNA methylation, posttranslational histone modifications, and involvement of small and long noncoding RNAs. Epigenetic changes have been linked to aspects of immune cell development, activation, and differentiation. Furthermore, genome-wide epigenetic landscapes have been established for some immune cells, including tissue-resident macrophages, and blood-derived cells including T cells. The epigenetic mechanisms underlying developmental steps from hematopoietic stem cells to fully differentiated immune cells led to development of epigenetic technologies and insights into general rules of epigenetic regulation. Compared with more advanced research areas, epigenetic reprogramming of immune cells in injury remains in its infancy. While the early epigenetic mechanisms supporting activation of the immune response to injury have been studied, less is known about resolution and repair phases and cell type–specific changes. We review prominent recent findings concerning injury-mediated epigenetic reprogramming, particularly in stroke and myocardial infarction. Lastly, we illustrate how single-cell technologies will be crucial to understanding epigenetic reprogramming in the complex sequential processes following injury.
Authors
Katarzyna Placek, Joachim L. Schultze, Anna C. Aschenbrenner
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Reviews
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Abstract
Development of novel and effective therapeutics for treating various cancers is probably the most congested and challenging enterprise of pharmaceutical companies. Diverse drugs targeting malignant and nonmalignant cells receive clinical approval each year from the FDA. Targeting cancer cells and nonmalignant cells unavoidably changes the tumor microenvironment, and cellular and molecular components relentlessly alter in response to drugs. Cancer cells often reprogram their metabolic pathways to adapt to environmental challenges and facilitate survival, proliferation, and metastasis. While cancer cells’ dependence on glycolysis for energy production is well studied, the roles of adipocytes and lipid metabolic reprogramming in supporting cancer growth, metastasis, and drug responses are less understood. This Review focuses on emerging mechanisms involving adipocytes and lipid metabolism in altering the response to cancer treatment. In particular, we discuss mechanisms underlying cancer-associated adipocytes and lipid metabolic reprogramming in cancer drug resistance.
Authors
Yihai Cao
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The gut microbiome is a key regulator of bone health that affects postnatal skeletal development and skeletal involution. Alterations in microbiota composition and host responses to the microbiota contribute to pathological bone loss, while changes in microbiota composition that prevent, or reverse, bone loss may be achieved by nutritional supplements with prebiotics and probiotics. One mechanism whereby microbes influence organs of the body is through the production of metabolites that diffuse from the gut into the systemic circulation. Recently, short-chain fatty acids (SCFAs), which are generated by fermentation of complex carbohydrates, have emerged as key regulatory metabolites produced by the gut microbiota. This Review will focus on the effects of SCFAs on the musculoskeletal system and discuss the mechanisms whereby SCFAs regulate bone cells.
Authors
Mario M. Zaiss, Rheinallt M. Jones, Georg Schett, Roberto Pacifici
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Commentaries
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Abstract
Solid organ transplantation from hepatitis C virus–positive (HCV-positive) deceased donors into HCV-negative recipients is a recent approach aimed to expand the donor organ pool in the setting of severe shortage. Good short-term outcomes have been reported with this approach in combination with direct-acting antivirals. In this issue of the JCI, Zahid and colleagues have characterized early viral kinetics and the genetic landscape of donor-to-recipient HCV transmission using single-genome sequencing. In seven HCV-negative recipients of four HCV-positive donor organs, productive infection with a highly diverse viral population was seen by day three after transplant. The degree of genetic diversity seen in recipients of HCV-positive organs was unlike the narrow genetic bottleneck typically observed with acute HCV acquisition from intravenous drug use or sexual activity. All recipients achieved HCV cure with treatment. The consequences of acute infection with a genetically diverse HCV population are unknown; however, early clinical experience with this transplantation strategy is promising.
Authors
Christine M. Durand, Michael A. Chattergoon
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Lactation is a unique period in which the maternal skeleton acts as a storehouse to provide substantial calcium to milk. Women who exclusively breastfeed lose an average of 210 mg of calcium per day, which doubles or triples with twins and triplets. Data from rodent and clinical studies are consistent with skeletal calcium being released to provide much of the calcium needed for milk production. This is programmed to occur independently of dietary calcium intake or intestinal calcium absorption, which remains at the prepregnant rate in breastfeeding women. After weaning, the skeleton is restored to its prior mineralization and strength, but the factors that regulate this remain to be elucidated.
Authors
Brittany A. Ryan, Christopher S. Kovacs
×Abstract
The discovery of insulin almost 100 years ago has resulted in a remarkable increase in lifespan and quality of life for patients with type 1 diabetes. The Joslin Medalist Study has allowed researchers to access and study patients (Medalists) with type 1 diabetes who have been insulin dependent for 50 years or more. In this issue of the JCI, Yu et al. evaluated HLA variants, autoantibody status, β cell function, C-peptide release, and monogenetic diabetes genes in a cohort of Medalists. Postmortem analysis of pancreata from Medalists revealed the presence of insulin-positive β cells in these patients. Moreover, some patients were still able to respond to metabolic stimuli despite long-term insulin dependence. Overall, the Medalist cohort was highly heterogenous, and genetic testing suggested that several patients would fall into categories other than type 1 diabetes on the basis of REVEL (rare exome variant ensemble learner) classification and may be able to transfer to other therapy options.
Authors
Fabrizio Barbetti, Simeon I. Taylor
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T follicular helper (Tfh) cells in germinal centers of secondary lymphoid organs are pivotal for B and T cell interactions required for induction of humoral immunity. It has long been debated whether Tfh cells exit from lymph nodes into the blood as circulating Tfh cells. In this issue of the JCI, Vella et al. have taken the bull by the horns and applied considerable technical muscle to answer this question. By analyzing phenotype, transcriptome, epigenetic profile, and T cell receptor clonotype, the authors provide evidence that a subset of cTfh cells do indeed originate in lymph nodes and traffic into the blood via the thoracic duct.
Authors
Savita Pahwa
×Abstract
Neurologic involvement of HIV remains an important concern for patients, physicians, and investigators. Catastrophic decline is rarely seen in patients on combination antiretroviral therapy (cART); however, neurological decline remains a critical clinical challenge. In this issue of the JCI, Spudich and associates investigated the status of HIV in the cerebral spinal fluid (CSF) and revealed ongoing presence of HIV in the nervous system. Surprisingly, even in the face of optimal treatment, including suppressed HIV RNA, almost half of the patients investigated showed cell-associated HIV (CA-HIV) DNA in the CSF. Spudich et al. find that persistence of HIV in CSF cells is associated with lower performance on neurocognitive testing. These findings emphasize the need to consider a viral-associated mechanism as playing a significant and potentially ongoing role in HIV-associated neurocognitive disorder (HAND).
Authors
David B. Clifford
×Abstract
Organ transplantation is now a preferred treatment for end-stage organ failure. Among the challenges for ensuring excellent clinical outcomes for transplant recipients is good initial allograft function at the time of organ implantation. This is determined in part by the functional status of the donor and donor organ, functional status of the recipient, and conduct of the operative procedure. Despite optimization of these variables, organ transplantation is still often plagued by substantial initial dysfunction, variably referred to as slow or delayed graft function, or in the most extreme cases, primary graft nonfunction necessitating urgent regrafting. In this issue of the JCI, Nakamura, Kageyama, Ito, Hirao, and colleagues investigate a potential role for the recipient’s microbiome in determining graft function after liver transplantation and demonstrate the benefits of antibiotic pretreatment in both a mouse model and in human patients.
Authors
Jonathan S. Bromberg, Joseph R. Scalea, Emmanuel F. Mongodin
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Research Articles
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Abstract
Lactation induces bone loss to provide sufficient calcium in the milk, a process that involves osteoclastic bone resorption but also osteocytes and perilacunar resorption. The exact mechanisms by which osteocytes contribute to bone loss remain elusive. Osteocytes express genes required in osteoclasts for bone resorption, including cathepsin K (Ctsk), and lactation elevates their expression. We show that Ctsk deletion in osteocytes prevented the increase in osteocyte lacunar area seen during lactation, as well as the effects of lactation to increase osteoclast numbers and decrease trabecular bone volume, cortical thickness, and mechanical properties. In addition, we show that Ctsk deletion in osteocytes increased bone parathyroid hormone–related peptide (PTHrP) and prevented the decrease in serum parathyroid hormone (PTH) induced by lactation, but amplified the increase in serum 1,25-dyhydroxyvitamin D [1,25(OH)2D]. The net result of these changes is to maintain serum and milk calcium levels in the normal range, ensuring normal offspring skeletal development. Our studies confirm the fundamental role of osteocytic perilacunar remodeling in physiological states of lactation and provide genetic evidence that osteocyte-derived Ctsk contributes not only to osteocyte perilacunar remodeling, but also to the regulation of PTH, PTHrP, 1,25(OH)2D, osteoclastogenesis, and bone loss in response to the high calcium demand associated with lactation.
Authors
Sutada Lotinun, Yoshihito Ishihara, Kenichi Nagano, Riku Kiviranta, Vincent T. Carpentier, Lynn Neff, Virginia Parkman, Noriko Ide, Dorothy Hu, Pamela Dann, Daniel Brooks, Mary L. Bouxsein, John Wysolmerski, Francesca Gori, Roland Baron
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Gliomas account for approximately 80% of primary malignant tumors in the central nervous system. Despite aggressive therapy, the prognosis of patients remains extremely poor. Glioma stem cells (GSCs), considered a potential target of therapy for their crucial role in therapeutic resistance and tumor recurrence, are believed to be key factors in the disappointing outcome. Here, we took advantage of GSCs as the cell model to perform high-throughput drug screening, and the old antibiotic clofoctol was identified as the most effective compound, showing reduction of colony formation and induction of apoptosis of GSCs. Moreover, growth of tumors was obviously inhibited in vivo after clofoctol treatment especially in primary patient-derived xenografts and transgenic xenografts. The anticancer mechanisms demonstrated by analysis of related downstream genes and discovery of the targeted binding protein revealed that clofoctol exhibited the inhibition of GSCs by upregulation of Krüppel-like factor 13 (KLF13), a tumor suppressor gene, through clofoctol’s targeted binding protein, Upstream of N-ras (UNR). Collectively, these data demonstrate that induction of KLF13 expression suppressed growth of gliomas and provide a potential therapy for gliomas targeting GSCs. Importantly, our results also identify the RNA-binding protein UNR as a drug target.
Authors
Yan Hu, Meilian Zhang, Ningyu Tian, Dengke Li, Fan Wu, Peishan Hu, Zhixing Wang, Liping Wang, Wei Hao, Jingting Kang, Bin Yin, Zhi Zheng, Tao Jiang, Jiangang Yuan, Boqin Qiang, Wei Han, Xiaozhong Peng
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Lymph nodes (LNs) filter lymph to mount effective immune responses. Small soluble lymph-borne molecules from the periphery enter the draining LNs via a reticular conduit system. Intact antibodies and other larger molecules, in contrast, are physically unable to enter the conduits, and they are thought to be transported to the LNs only within migratory DCs after proteolytic degradation. Here, we discovered that lymph-borne antibodies and other large biomolecules enter within seconds into the parenchyma of the draining LN in an intact form. Mechanistically, we found that the uptake of large molecules is a receptor-independent, fluid-phase process that takes place by dynamin-dependent vesicular transcytosis through the lymphatic endothelial cells in the subcapsular sinus of the LN. Physiologically, this pathway mediates a very fast transfer of large protein antigens from the periphery to LN-resident DCs and macrophages. We show that exploitation of the transcytosis system allows enhanced whole-organ imaging and spatially controlled lymphocyte activation by s.c. administered antibodies in vivo. Transcytosis through the floor of the subcapsular sinus thus represents what we believe to be a new physiological and targetable mode of lymph filtering.
Authors
Laura Kähäri, Ruth Fair-Mäkelä, Kaisa Auvinen, Pia Rantakari, Sirpa Jalkanen, Johanna Ivaska, Marko Salmi
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Mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis (ALS) are yet unclear. Specific deletion of the ER-component membralin in astrocytes manifested postnatal motor defects and lethality in mice, causing the accumulation of extracellular glutamate through reducing the glutamate transporter EAAT2. Restoring EAAT2 levels in membralin-KO astrocytes limited astrocyte-dependent excitotoxicity in motor neurons. Transcriptomic profiles from mouse astrocytic membralin-KO motor cortex indicated significant perturbation in KEGG pathway components related to ALS, including downregulation of Eaat2 and upregulation of Tnfrsf1a. Changes in gene expression with membralin deletion also overlapped with mouse ALS models and reactive astrocytes. Our results show that activation of the TNF receptor (TNFR1) NFκB pathway known to suppress Eaat2 transcription was upregulated with membralin deletion. Further, reduced membralin and EAAT2 levels correlated with disease progression in spinal cord from SOD1-mutant mouse models, and reductions in membralin/EAAT2 were observed in human ALS spinal cord. Importantly, overexpression of membralin in SOD1G93A astrocytes decreased TNFR1 levels and increased EAAT2 expression, and improved motor neuron survival. Importantly, upregulation of membralin in SOD1G93A mice significantly prolonged mouse survival. Our study provided a mechanism for ALS pathogenesis where membralin limited glutamatergic neurotoxicity, suggesting that modulating membralin had potential in ALS therapy.
Authors
Lu-Lin Jiang, Bing Zhu, Yingjun Zhao, Xiaoguang Li, Tongfei Liu, Juan Pina-Crespo, Lisa Zhou, Wenxi Xu, Maria J. Rodriguez, Haiyang Yu, Don W. Cleveland, John Ravits, Sandrine Da Cruz, Tao Long, Dongxian Zhang, Timothy Y. Huang, Huaxi Xu
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Lumen integrity in vascularization requires fully differentiated endothelial cells (ECs). Here, we report that endothelial-mesenchymal transitions (EndMTs) emerged in ECs of cerebral arteriovenous malformation (AVMs) and caused disruption of the lumen or lumen disorder. We show that excessive Sry-box 2 (Sox2) signaling was responsible for the EndMTs in cerebral AVMs. EC-specific suppression of Sox2 normalized endothelial differentiation and lumen formation and improved the cerebral AVMs. Epigenetic studies showed that induction of Sox2 altered the cerebral-endothelial transcriptional landscape and identified jumonji domain–containing protein 5 (JMJD5) as a direct target of Sox2. Sox2 interacted with JMJD5 to induce EndMTs in cerebral ECs. Furthermore, we utilized a high-throughput system to identify the β-adrenergic antagonist pronethalol as an inhibitor of Sox2 expression. Treatment with pronethalol stabilized endothelial differentiation and lumen formation, which limited the cerebral AVMs.
Authors
Jiayi Yao, Xiuju Wu, Daoqin Zhang, Lumin Wang, Li Zhang, Eric X. Reynolds, Carlos Hernandez, Kristina I. Boström, Yucheng Yao
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Highly effective direct-acting antivirals against hepatitis C virus (HCV) have created an opportunity to transplant organs from HCV-positive individuals into HCV-negative recipients, since de novo infection can be routinely cured. As this procedure is performed more widely, it becomes increasingly important to understand the biological underpinnings of virus transmission, especially the multiplicity of infection. Here, we used single genome sequencing of plasma virus in 4 genotype 1a HCV-positive organ donors and their 7 organ recipients to assess the genetic bottleneck associated with HCV transmission following renal and cardiac transplantation. In all recipients, de novo infection was established by multiple genetically distinct viruses that reflect the full phylogenetic spectrum of replication-competent virus circulating in donor plasma. This was true in renal and cardiac transplantation and in recipients with peak viral loads ranging between 2.9–6.6 log10 IU/mL. The permissive transmission process characterized here contrasts sharply with sexual or injection-related transmission, which occurs less frequently per exposure and is generally associated with a stringent genetic bottleneck. These findings highlight the effectiveness of current anti-HCV regimens while raising caution regarding the substantially higher multiplicity of infection seen in organ transplantation–associated HCV acquisition.
Authors
Muhammad N. Zahid, Shuyi Wang, Gerald H. Learn, Peter L. Abt, Emily A. Blumberg, Peter P. Reese, David S. Goldberg, George M. Shaw, Katharine J. Bar
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Elevated blood glucose (hyperglycemia) is a hallmark metabolic abnormality in diabetes. Hyperglycemia is associated with protein kinase A–dependent (PKA-dependent) stimulation of L-type Ca2+ channels in arterial myocytes resulting in increased vasoconstriction. However, the mechanisms by which glucose activates PKA remain unclear. Here, we showed that elevating extracellular glucose stimulates cAMP production in arterial myocytes, and that this was specifically dependent on adenylyl cyclase 5 (AC5) activity. Super-resolution imaging suggested nanometer proximity between subpopulations of AC5 and the L-type Ca2+ channel pore-forming subunit CaV1.2. In vitro, in silico, ex vivo, and in vivo experiments revealed that this close association is critical for stimulation of L-type Ca2+ channels in arterial myocytes and increased myogenic tone upon acute hyperglycemia. This pathway supported the increase in L-type Ca2+ channel activity and myogenic tone in 2 animal models of diabetes. Our collective findings demonstrate a unique role for AC5 in PKA-dependent modulation of L-type Ca2+ channel activity and vascular reactivity during acute hyperglycemia and diabetes.
Authors
Arsalan U. Syed, Gopireddy R. Reddy, Debapriya Ghosh, Maria Paz Prada, Matthew A. Nystoriak, Stefano Morotti, Eleonora Grandi, Padmini Sirish, Nipavan Chiamvimonvat, Johannes W. Hell, Luis F. Santana, Yang K. Xiang, Madeline Nieves-Cintrón, Manuel F. Navedo
×Abstract
Hedgehog (Hh) proteins regulate development and tissue homeostasis, but their role in atopic dermatitis (AD) remains unknown. We found that on induction of mouse AD, Sonic Hedgehog (Shh) expression in skin and Hh pathway action in skin T cells were increased. Shh signaling reduced AD pathology and the levels of Shh expression determined disease severity. Hh-mediated transcription in skin T cells in AD-induced mice increased Treg populations and their suppressive function through increased active transforming growth factor–β (TGF-β) in Treg signaling to skin T effector populations to reduce disease progression and pathology. RNA sequencing of skin CD4+ T cells from AD-induced mice demonstrated that Hh signaling increased expression of immunoregulatory genes and reduced expression of inflammatory and chemokine genes. Addition of recombinant Shh to cultures of naive human CD4+ T cells in iTreg culture conditions increased FOXP3 expression. Our findings establish an important role for Shh upregulation in preventing AD, by increased Gli-driven, Treg cell–mediated immune suppression, paving the way for a potential new therapeutic strategy.
Authors
Eleftheria Papaioannou, Diana C. Yánez, Susan Ross, Ching-In Lau, Anisha Solanki, Mira Manilal Chawda, Alex Virasami, Ismael Ranz, Masahiro Ono, Ryan F. L. O’Shaughnessy, Tessa Crompton
×Abstract
Arrhythmogenic cardiomyopathy (ACM) is an inherited arrhythmia syndrome characterized by severe structural and electrical cardiac phenotypes, including myocardial fibrofatty replacement and sudden cardiac death. Clinical management of ACM is largely palliative, owing to an absence of therapies that target its underlying pathophysiology, which stems partially from our limited insight into the condition. Following identification of deceased ACM probands possessing ANK2 rare variants and evidence of ankyrin-B loss of function on cardiac tissue analysis, an ANK2 mouse model was found to develop dramatic structural abnormalities reflective of human ACM, including biventricular dilation, reduced ejection fraction, cardiac fibrosis, and premature death. Desmosomal structure and function appeared preserved in diseased human and murine specimens in the presence of markedly abnormal β-catenin expression and patterning, leading to identification of a previously unknown interaction between ankyrin-B and β-catenin. A pharmacological activator of the WNT/β-catenin pathway, SB-216763, successfully prevented and partially reversed the murine ACM phenotypes. Our findings introduce what we believe to be a new pathway for ACM, a role of ankyrin-B in cardiac structure and signaling, a molecular link between ankyrin-B and β-catenin, and evidence for targeted activation of the WNT/β-catenin pathway as a potential treatment for this disease.
Authors
Jason D. Roberts, Nathaniel P. Murphy, Robert M. Hamilton, Ellen R. Lubbers, Cynthia A. James, Crystal F. Kline, Michael H. Gollob, Andrew D. Krahn, Amy C. Sturm, Hassan Musa, Mona El-Refaey, Sara Koenig, Meriam Åström Aneq, Edgar T. Hoorntje, Sharon L. Graw, Robert W. Davies, Muhammad Arshad Rafiq, Tamara T. Koopmann, Shabana Aafaqi, Meena Fatah, David A. Chiasson, Matthew R.G. Taylor, Samantha L. Simmons, Mei Han, Chantal J.M. van Opbergen, Loren E. Wold, Gianfranco Sinagra, Kirti Mittal, Crystal Tichnell, Brittney Murray, Alberto Codima, Babak Nazer, Duy T. Nguyen, Frank I. Marcus, Nara Sobriera, Elisabeth M. Lodder, Maarten P. van den Berg, Danna A. Spears, John F. Robinson, Philip C. Ursell, Anna K. Green, Allan C. Skanes, Anthony S. Tang, Martin J. Gardner, Robert A. Hegele, Toon A.B. van Veen, Arthur A.M. Wilde, Jeff S. Healey, Paul M.L. Janssen, Luisa Mestroni, J. Peter van Tintelen, Hugh Calkins, Daniel P. Judge, Thomas J. Hund, Melvin M. Scheinman, Peter J. Mohler
×Abstract
T follicular helper cells (Tfh), a subset of CD4+ T cells, provide requisite help to B cells in the germinal centers (GC) of lymphoid tissue. GC Tfh are identified by high expression of the chemokine receptor CXCR5 and the inhibitory molecule PD-1. Although more accessible, blood contains lower frequencies of CXCR5+ and PD-1+ cells that have been termed circulating Tfh (cTfh). However, it remains unclear whether GC Tfh exit lymphoid tissues and populate this cTfh pool. To examine exiting cells, we assessed the phenotype of Tfh present within the major conduit of efferent lymph from lymphoid tissues into blood, the human thoracic duct. Unlike what was found in blood, we consistently identified a CXCR5-bright PD-1–bright (CXCR5BrPD-1Br) Tfh population in thoracic duct lymph (TDL). These CXCR5BrPD-1Br TDL Tfh shared phenotypic and transcriptional similarities with GC Tfh. Moreover, components of the epigenetic profile of GC Tfh could be detected in CXCR5BrPD-1Br TDL Tfh and the transcriptional imprint of this epigenetic signature was enriched in an activated cTfh subset known to contain vaccine-responding cells. Together with data showing shared TCR sequences between the CXCR5BrPD-1Br TDL Tfh and cTfh, these studies identify a population in TDL as a circulatory intermediate connecting the biology of Tfh in blood to Tfh in lymphoid tissue.
Authors
Laura A. Vella, Marcus Buggert, Sasikanth Manne, Ramin S. Herati, Ismail Sayin, Leticia Kuri-Cervantes, Irene Bukh Brody, Kaitlin C. O’Boyle, Hagop Kaprielian, Josephine R. Giles, Son Nguyen, Alexander Muselman, Jack P. Antel, Amit Bar-Or, Matthew E. Johnson, David H. Canaday, Ali Naji, Vitaly V. Ganusov, Terri M. Laufer, Andrew D. Wells, Yoav Dori, Maxim G. Itkin, Michael R. Betts, E. John Wherry
×Abstract
Acute liver failure (ALF) is a life-threatening condition, and liver transplantation is the only therapeutic option. Although immune dysregulation is central to its pathogenesis, the precise mechanism remains unclear. Here, we show that the number of peripheral and hepatic plasmacytoid DCs (pDCs) decrease during acute liver injury in both humans and mice. Selective depletion of pDCs in Siglechdtr/+ mice exacerbated concanavalin A–induced acute liver injury. In contrast, adoptively transferred BM-derived pDCs preferentially accumulated in the inflamed liver and protected against liver injury. This protective effect was independent of TLR7 and TLR9 signaling, since a similar effect occurred following transfer of MyD88-deficient pDCs. Alternatively, we found an unexpected immunosuppressive role of pDCs in an IL-35–dependent manner. Both Il12a and Ebi3, heterodimeric components of IL-35, were highly expressed in transferred pDCs and CD4+CD25+ Tregs. However, the protective effect of pDC transfer was completely lost in mice depleted of Tregs by anti-CD25 antibody. Moreover, pDCs derived from IL-35–deficient mice had less of a protective effect both in vivo and in vitro even in the presence of Tregs. These results highlight a unique aspect of pDCs in association with Tregs, serving as a guide for immunotherapeutic options in ALF.
Authors
Yuzo Koda, Nobuhiro Nakamoto, Po-Sung Chu, Aya Ugamura, Yohei Mikami, Toshiaki Teratani, Hanako Tsujikawa, Shunsuke Shiba, Nobuhito Taniki, Tomohisa Sujino, Kentaro Miyamoto, Takahiro Suzuki, Akihiro Yamaguchi, Rei Morikawa, Katsuaki Sato, Michiie Sakamoto, Takayuki Yoshimoto, Takanori Kanai
×Abstract
Receptor activator of NF-κB ligand (RANKL) activates, while osteoprotegerin (OPG) inhibits, osteoclastogenesis. A neutralizing Ab against RANKL, denosumab, improves bone strength in osteoporosis. OPG also improves muscle strength in mouse models of Duchenne’s muscular dystrophy (mdx) and denervation-induced atrophy, but its role and mechanisms of action on muscle weakness in other conditions remain to be investigated. We investigated the effects of RANKL inhibitors on muscle in osteoporotic women and mice that either overexpress RANKL (HuRANKLTg+), or lack Pparb and concomitantly develop sarcopenia (Pparb–/–). In women, taking denosumab for more than 3 years improved appendicular lean mass and handgrip strength compared with no treatment, whereas bisphosphonate did not. HuRANKLTg+ mice displayed lower limb force and maximal speed, while their leg muscle mass was diminished, with a lower number of type I and II fibers. Both OPG and denosumab increased limb force proportionally to the increase in muscle mass. They markedly improved muscle insulin sensitivity and glucose uptake, and decreased antimyogenic and inflammatory gene expression in muscle, such as myostatin and protein tyrosine phosphatase receptor-γ. Similarly, in Pparb–/–, OPG increased muscle volume and force while also normalizing insulin signaling and higher expression of inflammatory genes in skeletal muscle. In conclusion, RANKL deteriorates while its inhibitors improve muscle strength and insulin sensitivity in osteoporotic mice and humans. Hence, denosumab could represent a novel therapeutic approach for sarcopenia.
Authors
Nicolas Bonnet, Lucie Bourgoin, Emmanuel Biver, Eleni Douni, Serge Ferrari
×Abstract
Epithelial barrier dysfunction is a significant factor in many allergic diseases, including eosinophilic esophagitis (EoE). Infiltrating leukocytes and tissue adaptations increase metabolic demands and decrease oxygen availability at barrier surfaces. Understanding of how these processes impact barrier is limited, particularly in allergy. Here, we identified a regulatory axis whereby the oxygen-sensing transcription factor HIF-1α orchestrated epithelial barrier integrity, selectively controlling tight junction CLDN1 (claudin-1). Prolonged experimental hypoxia or HIF1A knockdown suppressed HIF-1α–dependent claudin-1 expression and epithelial barrier function, as documented in 3D organotypic epithelial cultures. L2-IL5OXA mice with EoE-relevant allergic inflammation displayed localized eosinophil oxygen metabolism, tissue hypoxia, and impaired claudin-1 barrier via repression of HIF-1α/claudin-1 signaling, which was restored by transgenic expression of esophageal epithelial-targeted stabilized HIF-1α. EoE patient biopsy analysis identified a repressed HIF-1α/claudin-1 axis, which was restored via pharmacologic HIF-1α stabilization ex vivo. Collectively, these studies reveal HIF-1α’s critical role in maintaining barrier and highlight the HIF-1α/claudin-1 axis as a potential therapeutic target for EoE.
Authors
Joanne C. Masterson, Kathryn A. Biette, Juliet A. Hammer, Nathalie Nguyen, Kelley E. Capocelli, Bejan J. Saeedi, Rachel F. Harris, Shahan D. Fernando, Lindsay B. Hosford, Caleb J. Kelly, Eric L. Campbell, Stefan F. Ehrentraut, Faria N. Ahmed, Hiroshi Nakagawa, James J. Lee, Eóin N. McNamee, Louise E. Glover, Sean P. Colgan, Glenn T. Furuta
×Abstract
Tumorigenicity is a well-documented risk to overcome for pluripotent or multipotent cell applications in regenerative medicine. To address the emerging demand for safe cell sources in tissue regeneration, we established a novel, protein-based reprogramming method that does not require genome integration or oncogene activation to yield multipotent fibromodulin (FMOD)-reprogrammed (FReP) cells from dermal fibroblasts. When compared with induced pluripotent stem cells (iPSCs), FReP cells exhibited a superior capability for bone and skeletal muscle regeneration with markedly less tumorigenic risk. Moreover, we showed that the decreased tumorigenicity of FReP cells was directly related to an upregulation of cyclin-dependent kinase inhibitor 2B (CDKN2B) expression during the FMOD reprogramming process. Indeed, sustained suppression of CDKN2B resulted in tumorigenic, pluripotent FReP cells that formed teratomas in vivo that were indistinguishable from iPSC-derived teratomas. These results highlight the pivotal role of CDKN2B in cell fate determination and tumorigenic regulation and reveal an alternative pluripotent/multipotent cell reprogramming strategy that solely uses FMOD protein.
Authors
Zhong Zheng, Chenshuang Li, Pin Ha, Grace X. Chang, Pu Yang, Xinli Zhang, Jong Kil Kim, Wenlu Jiang, Xiaoxiao Pang, Emily A. Berthiaume, Zane Mills, Christos S. Haveles, Eric Chen, Kang Ting, Chia Soo
×Abstract
BACKGROUND In the Joslin Medalist Study (Medalists), we determined whether significant associations exist between β cell function and pathology and clinical characteristics.METHODS Individuals with type 1 diabetes (T1D) for 50 or more years underwent evaluation including HLA analysis, basal and longitudinal autoantibody (AAb) status, and β cell function by a mixed-meal tolerance test (MMTT) and a hyperglycemia/arginine clamp procedure. Postmortem analysis of pancreases from 68 Medalists was performed. Monogenic diabetes genes were screened for the entire cohort.RESULTS Of the 1019 Medalists, 32.4% retained detectable C-peptide levels (>0.05 ng/mL, median: 0.21 ng/mL). In those who underwent a MMTT (n = 516), 5.8% responded with a doubling of baseline C-peptide levels. Longitudinally (n = 181, median: 4 years), C-peptide levels increased in 12.2% (n = 22) and decreased in 37% (n = 67) of the Medalists. Among those with repeated MMTTs, 5.4% (3 of 56) and 16.1% (9 of 56) had waxing and waning responses, respectively. Thirty Medalists with baseline C-peptide levels of 0.1 ng/mL or higher underwent the clamp procedure, with HLA–/AAb– and HLA+/AAb– Medalists being most responsive. Postmortem examination of pancreases from 68 Medalists showed that all had scattered insulin-positive cells; 59 additionally had few insulin-positive cells within a few islets; and 14 additionally had lobes with multiple islets with numerous insulin-positive cells. Genetic analysis revealed that 280 Medalists (27.5%) had monogenic diabetes variants; in 80 (7.9%) of these Medalists, the variants were classified as “likely pathogenic” (rare exome variant ensemble learner [REVEL] >0.75).CONCLUSION All Medalists retained insulin-positive β cells, with many responding to metabolic stimuli even after 50 years of T1D. The Medalists were heterogeneous with respect to β cell function, and many with HLA+ diabetes risk alleles also had monogenic diabetes variants, indicating the importance of genetic testing for clinically diagnosed T1D.FUNDING Funding for this work was provided by the Dianne Nunnally Hoppes Fund; the Beatson Pledge Fund; the NIH, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK); and the American Diabetes Association (ADA).
Authors
Marc Gregory Yu, Hillary A. Keenan, Hetal S. Shah, Scott G. Frodsham, David Pober, Zhiheng He, Emily A. Wolfson, Stephanie D’Eon, Liane J. Tinsley, Susan Bonner-Weir, Marcus G. Pezzolesi, George Liang King
×Abstract
The presence of tumor-infiltrating T cells is associated with favorable patient outcomes, yet most pancreatic cancers are immunologically silent and resistant to currently available immunotherapies. Here we show using a syngeneic orthotopic implantation model of pancreatic cancer that Pik3ca regulates tumor immunogenicity. Genetic silencing of Pik3ca in KrasG12D/Trp53R172H-driven pancreatic tumors resulted in infiltration of T cells, complete tumor regression, and 100% survival of immunocompetent host mice. By contrast, Pik3ca-null tumors implanted in T cell–deficient mice progressed and killed all of the animals. Adoptive transfer of tumor antigen–experienced T cells eliminated Pik3ca-null tumors in immunodeficient mice. Loss of PIK3CA or inhibition of its effector AKT increased the expression of MHC class I and CD80 on tumor cells. These changes contributed to the increased susceptibility of Pik3ca-null tumors to T cell surveillance. Our results indicate that tumor cell PIK3CA-AKT signaling limits T cell recognition and clearance of pancreatic cancer cells. Strategies that target this pathway may yield an effective immunotherapy for this cancer.
Authors
Nithya Sivaram, Patrick A. McLaughlin, Han V. Han, Oleksi Petrenko, Ya-Ping Jiang, Lisa M. Ballou, Kien Pham, Chen Liu, Adrianus W.M. van der Velden, Richard Z. Lin
×Abstract
The migration of leukocytes into the CNS drives the neuropathology of multiple sclerosis (MS). It is likely that this penetration utilizes energy resources that remain to be defined. Using the experimental autoimmune encephalomyelitis (EAE) model of MS, we determined that macrophages within the perivascular cuff of postcapillary venules are highly glycolytic, as manifested by strong expression of lactate dehydrogenase A (LDHA), which converts pyruvate to lactate. These macrophages expressed prominent levels of monocarboxylate transporter-4 (MCT-4), which is specialized in the secretion of lactate from glycolytic cells. The functional relevance of glycolysis was confirmed by siRNA-mediated knockdown of LDHA and MCT-4, which decreased lactate secretion and macrophage transmigration. MCT-4 was in turn regulated by EMMPRIN (also known as CD147), as determined through coexpression and co-IP studies and siRNA-mediated EMMPRIN silencing. The functional relevance of MCT-4–EMMPRIN interaction was confirmed by lower macrophage transmigration in culture using the MCT-4 inhibitor α-cyano-4-hydroxy-cinnamic acid (CHCA), a cinnamon derivative. CHCA also reduced leukocyte infiltration and the clinical severity of EAE. Relevance to MS was corroborated by the strong expression of MCT-4, EMMPRIN, and LDHA in perivascular macrophages in MS brains. These results detail the metabolism of macrophages for transmigration from perivascular cuffs into the CNS parenchyma and identify CHCA and diet as potential modulators of neuroinflammation in MS.
Authors
Deepak Kumar Kaushik, Anindita Bhattacharya, Reza Mirzaei, Khalil S. Rawji, Younghee Ahn, Jong M. Rho, V. Wee Yong
×Abstract
Idiopathic pulmonary fibrosis (IPF) is a deadly disease with limited therapies. Tissue fibrosis is associated with type 2 immune response, although the causal contribution of immune cells is not defined. The AP-1 transcription factor Fra-2 is upregulated in IPF lung sections, and Fra-2 transgenic mice (Fra-2Tg) exhibit spontaneous lung fibrosis. Here, we show that bleomycin-induced lung fibrosis is attenuated upon myeloid inactivation of Fra-2 and aggravated in Fra-2Tg bone marrow chimeras. Type VI collagen (ColVI), a Fra-2 transcriptional target, is upregulated in 3 lung fibrosis models, and macrophages promote myofibroblast activation in vitro in a ColVI- and Fra-2–dependent manner. Fra-2 or ColVI inactivation does not affect macrophage recruitment and alternative activation, suggesting that Fra-2/ColVI specifically controls the paracrine profibrotic activity of macrophages. Importantly, ColVI-KO mice and ColVI-KO bone marrow chimeras are protected from bleomycin-induced lung fibrosis. Therapeutic administration of a Fra-2/AP-1 inhibitor reduces ColVI expression and ameliorates fibrosis in Fra-2Tg mice and in the bleomycin model. Finally, Fra-2 and ColVI positively correlate in IPF patient samples and colocalize in lung macrophages. Therefore, the Fra-2/ColVI profibrotic axis is a promising biomarker and therapeutic target for lung fibrosis and possibly other fibrotic diseases.
Authors
Alvaro C. Ucero, Latifa Bakiri, Ben Roediger, Masakatsu Suzuki, Maria Jimenez, Pratyusha Mandal, Paola Braghetta, Paolo Bonaldo, Luis Paz-Ares, Coral Fustero-Torre, Pilar Ximenez-Embun, Ana Isabel Hernandez, Diego Megias, Erwin F. Wagner
×Abstract
Cytosolic arginine sensor for mTORC1 subunits 1 and 2 (CASTOR1 and CASTOR2) inhibit the mammalian target of rapamycin complex 1 (mTORC1) upon arginine deprivation. mTORC1 regulates cell proliferation, survival, and metabolism and is often dysregulated in cancers, indicating that cancer cells may regulate CASTOR1 and CASTOR2 to control mTORC1 signaling and promote tumorigenesis. mTORC1 is the most effective therapeutic target of Kaposi sarcoma, which is caused by infection with the Kaposi sarcoma–associated herpesvirus (KSHV). Hence, KSHV-induced cellular transformation is a suitable model for investigating mTORC1 regulation in cancer cells. Currently, the mechanism of KSHV activation of mTORC1 in KSHV-induced cancers remains unclear. We showed that KSHV suppressed CASTOR1 and CASTOR2 expression to activate the mTORC1 pathway. CASTOR1 or CASTOR2 overexpression and mTOR inhibitors abolished cell proliferation and colony formation in soft agar of KSHV-transformed cells by attenuating mTORC1 activation. Furthermore, the KSHV-encoded miRNA miR-K4-5p, and probably miR-K1-5p, directly targeted CASTOR1 to inhibit its expression. Knockdown of miR-K1-5p and -K4-5p restored CASTOR1 expression and thereby attenuated mTORC1 activation. Overexpression of CASTOR1 or CASTOR2 and mTOR inhibitors abolished the activation of mTORC1 and growth transformation induced by pre–miR-K1 and -K4. Our results define the mechanism of KSHV activation of the mTORC1 pathway and establish the scientific basis for targeting this pathway to treat KSHV-associated cancers.
Authors
Tingting Li, Enguo Ju, Shou-Jiang Gao
×Abstract
Glycosylation of immune receptors and ligands, such as T cell receptor and coinhibitory molecules, regulates immune signaling activation and immune surveillance. However, how oncogenic signaling initiates glycosylation of coinhibitory molecules to induce immunosuppression remains unclear. Here we show that IL-6–activated JAK1 phosphorylates programmed death-ligand 1 (PD-L1) Tyr112, which recruits the endoplasmic reticulum–associated N-glycosyltransferase STT3A to catalyze PD-L1 glycosylation and maintain PD-L1 stability. Targeting of IL-6 by IL-6 antibody induced synergistic T cell killing effects when combined with anti–T cell immunoglobulin mucin-3 (anti–Tim-3) therapy in animal models. A positive correlation between IL-6 and PD-L1 expression was also observed in hepatocellular carcinoma patient tumor tissues. These results identify a mechanism regulating PD-L1 glycosylation initiation and suggest the combination of anti–IL-6 and anti–Tim-3 as an effective marker-guided therapeutic strategy.
Authors
Li-Chuan Chan, Chia-Wei Li, Weiya Xia, Jung-Mao Hsu, Heng-Huan Lee, Jong-Ho Cha, Hung-Ling Wang, Wen-Hao Yang, Er-Yen Yen, Wei-Chao Chang, Zhengyu Zha, Seung-Oe Lim, Yun-Ju Lai, Chunxiao Liu, Jielin Liu, Qiongzhu Dong, Yi Yang, Linlin Sun, Yongkun Wei, Lei Nie, Jennifer L. Hsu, Hui Li, Qinghai Ye, Manal M. Hassan, Hesham M. Amin, Ahmed O. Kaseb, Xin Lin, Shao-Chun Wang, Mien-Chie Hung
×Abstract
BACKGROUND Persistence of HIV in sanctuary sites despite antiretroviral therapy (ART) presents a barrier to HIV remission and may affect neurocognitive function. We assessed HIV persistence in cerebrospinal fluid (CSF) and associations with inflammation and neurocognitive performance during long-term ART.METHODS Participants enrolled in the AIDS Clinical Trials Group (ACTG) HIV Reservoirs Cohort Study (A5321) underwent concurrent lumbar puncture, phlebotomy, and neurocognitive assessment. Cell-associated HIV DNA and HIV RNA (CA-DNA, CA-RNA) were measured by quantitative PCR (qPCR). in peripheral blood mononuclear cells (PBMCs) and in cell pellets from CSF. In CSF supernatant and blood plasma, cell-free HIV RNA was quantified by qPCR with single copy sensitivity, and inflammatory biomarkers were measured by enzyme immunoassay.RESULTS Sixty-nine participants (97% male, median age 50 years, CD4 696 cells/mm3, plasma HIV RNA <100 copies/mL) were assessed after a median 8.6 years of ART. In CSF, cell-free RNA was detected in 4%, CA-RNA in 9%, and CA-DNA in 48% of participants (median level 2.1 copies/103 cells). Detection of cell-free CSF HIV RNA was associated with higher plasma HIV RNA (P = 0.007). CSF inflammatory biomarkers did not correlate with HIV persistence measures. Detection of CSF CA-DNA HIV was associated with worse neurocognitive outcomes including global deficit score (P = 0.005), even after adjusting for age and nadir CD4 count.CONCLUSION HIV-infected cells persist in CSF in almost half of individuals on long-term ART, and their detection is associated with poorer neurocognitive performance.FUNDING This observational study, AIDS Clinical Trials Group (ACTG) HIV Reservoirs Cohort Study (A5321), was supported by the National Institutes of Health (NIAID and NIMH).
Authors
Serena Spudich, Kevin R. Robertson, Ronald J. Bosch, Rajesh T. Gandhi, Joshua C. Cyktor, Hanna Mar, Bernard J. Macatangay, Christina M. Lalama, Charles Rinaldo, Ann C. Collier, Catherine Godfrey, Joseph J. Eron, Deborah McMahon, Jana L. Jacobs, Dianna Koontz, Evelyn Hogg, Alyssa Vecchio, John W. Mellors
×Abstract
Programmed death-1 receptor ligand 1 (PD-L1) is a promising therapeutic target in aggressive cancers. However, immune landscapes and cancer hallmarks of human PD-L1+ tumors as well as their roles in determining therapeutic efficacies are unknown. Here, we showed, in detailed studies of gene data regarding 9769 patients of 32 types of human cancers, that PD-L1 could not exclusively represent the IFN-γ signature and potentially signified proinflammatory myeloid responses in a tumor. PD-L1 heterogeneity endowed by local immune landscapes controlled cancer hallmarks and clinical outcomes of patients. Mechanically, NF-κB signal elicited by macrophage inflammatory responses generated PD-L1+ cancer cells exhibiting capabilities to aggressively survive, support angiogenesis, and metastasize, whereas STAT1 signal triggered by activated T cells induced PD-L1+ cancer cells susceptive to apoptosis. Importantly, PD-L1+ cancer cells generated by macrophages established great resistance to conventional chemotherapy, cytotoxicity of tumor-specific effector T cells, and therapy of immune-checkpoint blockade. Therapeutic strategy combining immune-checkpoint blockade with macrophage depletion or NF-κB inhibition in vivo effectively and successfully elicited cancer regression. Our results provide insight into the functional features of PD-L1+ tumors and suggest that strategies to influence functional activities of inflammatory cells may benefit immune-checkpoint blockade therapy.
Authors
Yuan Wei, Qiyi Zhao, Zhiliang Gao, Xiang-Ming Lao, Wei-Ming Lin, Dong-Ping Chen, Ming Mu, Chun-Xiang Huang, Zheng-Yu Liu, Bo Li, Limin Zheng, Dong-Ming Kuang
×Abstract
HIV integrates its provirus into the host genome and establishes latent infection. Antiretroviral therapy (ART) can control HIV viremia, but cannot eradicate or cure the virus. Approaches targeting host epigenetic machinery to repress HIV, leading to an aviremic state free of ART, are needed. Bromodomain and extraterminal (BET) family protein BRD4 is an epigenetic reader involved in HIV transcriptional regulation. Using structure-guided drug design, we identified a small molecule (ZL0580) that induced epigenetic suppression of HIV via BRD4. We showed that ZL0580 induced HIV suppression in multiple in vitro and ex vivo cell models. Combination treatment of cells of aviremic HIV-infected individuals with ART and ZL0580 revealed that ZL0580 accelerated HIV suppression during ART and delayed viral rebound after ART cessation. Mechanistically different from the BET/BRD4 pan-inhibitor JQ1, which nonselectively binds to BD1 and BD2 domains of all BET proteins, ZL0580 selectively bound to BD1 domain of BRD4. We further demonstrate that ZL0580 induced HIV suppression by inhibiting Tat transactivation and transcription elongation as well as by inducing repressive chromatin structure at the HIV promoter. Our findings establish a proof of concept for modulation of BRD4 to epigenetically suppress HIV and provide a promising chemical scaffold for the development of probes and/or therapeutic agents for HIV epigenetic silencing.
Authors
Qingli Niu, Zhiqing Liu, Edrous Alamer, Xiuzhen Fan, Haiying Chen, Janice Endsley, Benjamin B. Gelman, Bing Tian, Jerome H. Kim, Nelson L. Michael, Merlin L. Robb, Jintanat Ananworanich, Jia Zhou, Haitao Hu
×Abstract
Oxidative stress plays an important role in aging-related neurodegeneration. This study used littermates of WT and Nox2-knockout (Nox2KO) mice plus endothelial cell–specific human Nox2 overexpression–transgenic (HuNox2Tg) mice to investigate Nox2-derived ROS in brain aging. Compared with young WT mice (3–4 months), aging WT mice (20–22 months) had obvious metabolic disorders and loss of locomotor activity. Aging WT brains had high levels of angiotensin II (Ang II) and ROS production; activation of ERK1/2, p53, and γH2AX; and losses of capillaries and neurons. However, these abnormalities were markedly reduced in aging Nox2KO brains. HuNox2Tg brains at middle age (11–12 months) already had high levels of ROS production and activation of stress signaling pathways similar to those found in aging WT brains. The mechanism of Ang II–induced endothelial Nox2 activation in capillary damage was examined using primary brain microvascular endothelial cells. The clinical significance of Nox2-derived ROS in aging-related loss of cerebral capillaries and neurons was investigated using postmortem midbrain tissues of young (25–38 years) and elderly (61–85 years) adults. In conclusion, Nox2 activation is an important mechanism in aging-related cerebral capillary rarefaction and reduced brain function, with the possibility of a key role for endothelial cells.
Authors
Lampson M. Fan, Li Geng, Sarah Cahill-Smith, Fangfei Liu, Gillian Douglas, Chris-Anne Mckenzie, Colin Smith, Gavin Brooks, Keith M. Channon, Jian-Mei Li
×Abstract
Fibroblasts from patients with Tangier disease carrying ATP-binding cassette A1 (ABCA1) loss-of-function mutations are characterized by cardiolipin accumulation, a mitochondrial-specific phospholipid. Suppression of ABCA1 expression occurs in glomeruli from patients with diabetic kidney disease (DKD) and in human podocytes exposed to DKD sera collected prior to the development of DKD. We demonstrated that siRNA ABCA1 knockdown in podocytes led to reduced oxygen consumption capabilities associated with alterations in the oxidative phosphorylation (OXPHOS) complexes and with cardiolipin accumulation. Podocyte-specific deletion of Abca1 (Abca1fl/fl) rendered mice susceptible to DKD, and pharmacological induction of ABCA1 improved established DKD. This was not mediated by free cholesterol, as genetic deletion of sterol-o-acyltransferase-1 (SOAT1) in Abca1fl/fl mice was sufficient to cause free cholesterol accumulation but did not cause glomerular injury. Instead, cardiolipin mediates ABCA1-dependent susceptibility to podocyte injury, as inhibition of cardiolipin peroxidation with elamipretide improved DKD in vivo and prevented ABCA1-dependent podocyte injury in vitro and in vivo. Collectively, we describe a pathway definitively linking ABCA1 deficiency to cardiolipin-driven mitochondrial dysfunction. We demonstrated that this pathway is relevant to DKD and that ABCA1 inducers or inhibitors of cardiolipin peroxidation may each represent therapeutic strategies for the treatment of established DKD.
Authors
G. Michelle Ducasa, Alla Mitrofanova, Shamroop K. Mallela, Xiaochen Liu, Judith Molina, Alexis Sloan, Christopher E. Pedigo, Mengyuan Ge, Javier Varona Santos, Yanio Hernandez, Jin-Ju Kim, Cyrille Maugeais, Armando J. Mendez, Viji Nair, Matthias Kretzler, George W. Burke, Robert G. Nelson, Yu Ishimoto, Reiko Inagi, Santanu Banerjee, Shaoyi Liu, Hazel H. Szeto, Sandra Merscher, Flavia Fontanesi, Alessia Fornoni
×Abstract
Transcription factor fusion genes create oncoproteins that drive oncogenesis and represent challenging therapeutic targets. Understanding the molecular targets by which such fusion oncoproteins promote malignancy offers an approach to develop rational treatment strategies to improve clinical outcomes. Capicua–double homeobox 4 (CIC-DUX4) is a transcription factor fusion oncoprotein that defines certain undifferentiated round cell sarcomas with high metastatic propensity and poor clinical outcomes. The molecular targets regulated by the CIC-DUX4 oncoprotein that promote this aggressive malignancy remain largely unknown. We demonstrated that increased expression of ETS variant 4 (ETV4) and cyclin E1 (CCNE1) occurs via neomorphic, direct effects of CIC-DUX4 and drives tumor metastasis and survival, respectively. We uncovered a molecular dependence on the CCNE-CDK2 cell cycle complex that renders CIC-DUX4–expressing tumors sensitive to inhibition of the CCNE-CDK2 complex, suggesting a therapeutic strategy for CIC-DUX4–expressing tumors. Our findings highlight a paradigm of functional diversification of transcriptional repertoires controlled by a genetically aberrant transcriptional regulator, with therapeutic implications.
Authors
Ross A. Okimoto, Wei Wu, Shigeki Nanjo, Victor Olivas, Yone K. Lin, Rovingaile Kriska Ponce, Rieko Oyama, Tadashi Kondo, Trever G. Bivona
×Abstract
The precise regulation of synaptic dopamine (DA) content by the DA transporter (DAT) ensures the phasic nature of the DA signal, which underlies the ability of DA to encode reward prediction error, thereby driving motivation, attention, and behavioral learning. Disruptions to the DA system are implicated in a number of neuropsychiatric disorders, including attention deficit hyperactivity disorder (ADHD) and, more recently, autism spectrum disorder (ASD). An ASD-associated de novo mutation in the SLC6A3 gene resulting in a threonine-to-methionine substitution at site 356 (DAT T356M) was recently identified and has been shown to drive persistent reverse transport of DA (i.e., anomalous DA efflux) in transfected cells and to drive hyperlocomotion in Drosophila melanogaster. A corresponding mutation in the leucine transporter, a DAT-homologous transporter, promotes an outward-facing transporter conformation upon substrate binding, a conformation possibly underlying anomalous DA efflux. Here, we investigated in vivo the impact of this ASD-associated mutation on DA signaling and ASD-associated behaviors. We found that mice homozygous for this mutation displayed impaired striatal DA neurotransmission and altered DA-dependent behaviors that correspond with some of the behavioral phenotypes observed in ASD.
Authors
Gabriella E. DiCarlo, Jenny I. Aguilar, Heinrich J.G. Matthies, Fiona E. Harrison, Kyle E. Bundschuh, Alyssa West, Parastoo Hashemi, Freja Herborg, Mattias Rickhag, Hao Chen, Ulrik Gether, Mark T. Wallace, Aurelio Galli
×Abstract
Although modifications of gut microbiota with antibiotics (Abx) influence mouse skin and cardiac allografts, its role in orthotopic liver transplantation (OLT) remains unknown. We aimed to determine whether and how recipient Abx pretreatment may affect hepatic ischemia-reperfusion injury (IRI) and OLT outcomes. Mice (C57BL/6) with or without Abx treatment (10 days) were transplanted with allogeneic (BALB/c) cold-stored (18 hours) livers, followed by liver and blood sampling (6 hours). We divided 264 human OLT recipients on the basis of duration of pre-OLT Abx treatment into control (Abx-free/Abx <10 days; n = 108) and Abx treatment (Abx ≥10days; n = 156) groups; OLT biopsy (Bx) samples were collected 2 hours after OLT (n = 52). Abx in mice mitigated IRI-stressed OLT (IRI-OLT), decreased CCAAT/enhancer-binding protein homologous protein (CHOP) (endoplasmic reticulum [ER] stress), enhanced LC3B (autophagy), and inhibited inflammation, whereas it increased serum prostaglandin E2 (PGE2) and hepatic PGE2 receptor 4 (EP4) expression. PGE2 increased EP4, suppressed CHOP, and induced autophagosome formation in hepatocyte cultures in an EP4-dependent manner. An EP4 antagonist restored CHOP, suppressed LC3B, and recreated IRI-OLT. Remarkably, human recipients of Abx treatment plus OLT (Abx-OLT), despite severe pretransplantation clinical acuity, had higher EP4 and LC3B levels but lower CHOP levels, which coincided with improved hepatocellular function (serum aspartate aminotransferase/serum aspartate aminotransferase [sALT/sAST]) and a decreased incidence of early allograft dysfunction (EAD). Multivariate analysis identified “Abx-free/Abx <10 days” as a predictive factor of EAD. This study documents the benefits of Abx pretreatment in liver transplant recipients, identifies ER stress and autophagy regulation by the PGE2/EP4 axis as a homeostatic underpinning, and points to the microbiome as a therapeutic target in OLT.
Authors
Kojiro Nakamura, Shoichi Kageyama, Takahiro Ito, Hirofumi Hirao, Kentaro Kadono, Antony Aziz, Kenneth J. Dery, Matthew J. Everly, Kojiro Taura, Shinji Uemoto, Douglas G. Farmer, Fady M. Kaldas, Ronald W. Busuttil, Jerzy W. Kupiec-Weglinski
×Abstract
Irreversible T cell exhaustion limits the efficacy of programmed cell death 1 (PD-1) blockade. We observed that dual CD40-TLR4 stimulation within a single tumor restored PD-1 sensitivity and that this regimen triggered a systemic tumor-specific CD8+ T cell response. This approach effectively treated established tumors in diverse syngeneic cancer models, and the systemic effect was dependent on the injected tumor, indicating that treated tumors were converted into necessary components of this therapy. Strikingly, this approach was associated with the absence of exhausted PD-1hi T cells in treated and distant tumors, while sparing the intervening draining lymph node and spleen. Furthermore, patients with transcription changes like those induced by this therapy experienced improved progression-free survival with anti–PD-1 treatment. Dual CD40-TLR4 activation within a single tumor is thus an approach for overcoming resistance to PD-1 blockade that is unique in its ability to cause the loss of exhausted T cells within tumors while sparing nonmalignant tissues.
Authors
Danny N. Khalil, Nathan Suek, Luis Felipe Campesato, Sadna Budhu, David Redmond, Robert M. Samstein, Chirag Krishna, Katherine S. Panageas, Marinela Capanu, Sean Houghton, Daniel Hirschhorn, Roberta Zappasodi, Rachel Giese, Billel Gasmi, Michael Schneider, Aditi Gupta, James J. Harding, John Alec Moral, Vinod P. Balachandran, Jedd D. Wolchok, Taha Merghoub
×Abstract
Cystic fibrosis (CF) is a multiorgan progressive genetic disease caused by loss of functional cystic fibrosis transmembrane conductance regulator (CFTR) channel. Previously, we identified a significant dysfunction in CF cells and model mice of the transcription factor nuclear factor E2–related factor-2 (Nrf2), a major regulator of redox balance and inflammatory signaling. Here we report that the approved F508del CFTR correctors VX809 and VX661 recover diminished Nrf2 function and colocalization with CFTR in CF human primary bronchial epithelia by proximity ligation assay, immunoprecipitation, and immunofluorescence, concordant with CFTR correction. F508del CFTR correctors induced Nrf2 nuclear translocation, Nrf2-dependent luciferase activity, and transcriptional activation of target genes. Rescue of Nrf2 function by VX809/VX661 was dependent on significant correction of F508del and was blocked by inhibition of corrected channel function, or high-level shRNA knockdown of CFTR or F508del CFTR. Mechanistically, F508del CFTR modulation restored Nrf2 phosphorylation and its interaction with the coactivator CREB-binding protein (CBP). Our findings demonstrate that sufficient modulation of F508del CFTR function corrects Nrf2 dysfunction in CF.
Authors
Dana C. Borcherding, Matthew E. Siefert, Songbai Lin, John Brewington, Hesham Sadek, John P. Clancy, Scott M. Plafker, Assem G. Ziady
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)