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Citation Information: J Clin Invest. 2019. https://doi.org/10.1172/JCI124508.
Abstract
Upon arterial injury, endothelial denudation leads to platelet activation, and delivery of multiple agents (e.g. TXA2, PDGF) promoting VSMC dedifferentiation, and proliferation, in injury repair (intimal hyperplasia). Resolution of vessel injury repair, and prevention of excessive repair (switching VSMC back to a differentiated quiescent state) is a poorly understood process. We now report that internalization of activated platelets by VSMCs promotes resolution of arterial injury by switching on VSMC quiescence. Ex vivo and in vivo studies using lineage tracing reporter mice (PF4-Cre x mTmG) demonstrated uptake of green platelets by red vascular smooth muscle cells upon arterial wire injury. Genome-wide miRNA sequencing of VSMCs co-cultured with activated platelets identified significant increases in platelet-derived miR-223. miR-223 appears to directly target PDGFRβ (in VSMCs) reversing the injury-induced dedifferentiation. Upon arterial injury platelet miR-223 knockout mice exhibit increased intimal hyperplasia, whereas miR-223 mimics reduced intimal hyperplasia. Diabetic mice with reduced expression of miR-223, exhibited enhanced VSMC dedifferentiation, proliferation, and increased intimal hyperplasia. Horizontal transfer of platelet-derived miRNAs into VSMCs provide a novel mechanism for regulating VSMC phenotypic switching. Platelets thus play a dual role in vascular injury repair, initiating an immediate repair process, and concurrently, a delayed process to prevent excessive repair.
Authors
Zhi Zeng, Luoxing Xia, Xuejiao Fan, Allison C. Ostriker, Timur Yarovinsky, Meiling Su, Yuan Zhang, Xiangwen Peng, Xie Yi, Lei Pi, Xiaoqiong Gu, Sookja Kim Chung, Kathleen A. Martin, Renjing Liu, John Hwa, Wai Ho Tang
Citation Information: J Clin Invest. 2019. https://doi.org/10.1172/JCI125456.
Abstract
Allergen immunotherapy for patients with allergies begins with weekly escalating doses of allergen under medial supervision to monitor and treat IgE-mast cell mediated anaphylaxis. There is currently no treatment to safely desensitize mast cells to enable robust allergen immunotherapy with therapeutic levels of allergen. Here we demonstrated that liposomal nanoparticles bearing an allergen and a high-affinity glycan ligand of the inhibitory receptor CD33 profoundly suppressed IgE-mediated activation of mast cells, prevented anaphylaxis in transgenic mice with mast cells expressing human CD33, and desensitized mice from subsequent allergen challenge for several days. We showed that high levels of CD33 were consistently expressed on human skin mast cells, and that the antigenic-liposomes with CD33 ligand prevented IgE-mediated bronchoconstriction in slices of human lung. The results demonstrated the potential of exploiting CD33 to desensitize mast cells to provide a therapeutic window for administering allergen immunotherapy without triggering anaphylaxis.
Authors
Shiteng Duan, Cynthia J. Koziol-White, William F. Jester Jr., Corwin M. Nycholat, Matthew S. Macauley, Reynold A. Panettieri Jr., James C. Paulson
Citation Information: J Clin Invest. 2019. https://doi.org/10.1172/JCI97642.
Abstract
Immune checkpoint inhibitors and adoptive transfer of gene-engineered T cells have emerged as novel therapeutic modalities for hard-to-treat solid tumors; however, many patients are refractory to these immunotherapies, and the mechanisms underlying tumor immune resistance have not been fully elucidated. By comparing the tumor microenvironment of checkpoint inhibition-sensitive and -resistant murine solid tumors, we observed that the resistant tumors had low immunogenicity and lacked infiltration of CD8+ T cells at the tumor site. We identified antigen presentation by CD11b+F4/80+ tumor-associated macrophages (TAMs) as a key factor correlated with immune resistance. In the resistant tumors, TAMs remained inactive and did not exert antigen-presenting activity. Targeted delivery of a long peptide antigen to TAMs by using a nano-sized hydrogel (nanogel) in the presence of a Toll-like receptor agonist activated TAMs, induced their antigen-presenting activity, and thereby transformed the resistant tumors into tumors sensitive to adaptive immune responses such as adoptive transfer of tumor-specific T cell receptor-engineered T cells. These results indicate that the status and function of TAMs have a significant impact on tumor immune sensitivity and also that manipulation of TAM functions would be an effective approach for improving the efficacy of immunotherapies.
Authors
Daisuke Muraoka, Naohiro Seo, Tae Hayashi, Yoshiro Tahara, Keisuke Fujii, Isao Tawara, Yoshihiro Miyahara, Kana Okamori, Hideo Yagita, Seiya Imoto, Rui Yamaguchi, Mitsuhiro Komura, Satoru Miyano, Masahiro Goto, Shin-ichi Sawada, Akira Asai, Hiroaki Ikeda, Kazunari Akiyoshi, Naozumi Harada, Hiroshi Shiku
Citation Information: J Clin Invest. 2019. https://doi.org/10.1172/JCI122440.
Abstract
Local flow patterns determine the uneven distribution of atherosclerotic lesions. This research aims to elucidate the mechanism of regulation of nuclear translocation of Yes-associated protein (YAP) under oscillatory shear stress (OSS) in the atheroprone phenotype of endothelial cells (ECs). We report here that OSS led to tyrosine phosphorylation and strong, continuous nuclear translocation of YAP in ECs that is dependent on integrin α5β1 activation. YAP overexpression in ECs blunted the anti-atheroprone effect of an integrin-α5β1 blocking peptide (ATN161) in Apoe-/- mice. Activation of integrin α5β1 induced tyrosine, but not serine, phosphorylation of YAP in ECs. Blockage of integrin α5β1 with ATN161 abolished the phosphorylation of YAP at Y357 induced by OSS. Mechanistic studies showed that c-Abl inhibitor attenuated the integrin α5β1-induced YAP tyrosine phosphorylation. Furthermore, the phosphorylation of c-Abl and YAPY357 was significantly increased in ECs in atherosclerotic vessels of mice and in human plaques vs. normal vessels. Finally, bosutinib, a tyrosine kinase inhibitor, markedly reduced the level of YAPY357 and the development of atherosclerosis in Apoe-/- mice. The c-Abl/YAPY357 pathway serves as a mechanism for the activation of integrin α5β1 and the atherogenic phenotype of ECs in response to OSS, and provides a potential therapeutic strategy for atherogenesis.
Authors
Bochuan Li, Jinlong He, Huizhen Lv, Yajin Liu, Xue Lv, Chenghu Zhang, Yi Zhu, Ding Ai
Citation Information: J Clin Invest. 2019. https://doi.org/10.1172/JCI123959.
Abstract
Sphingolipid imbalance is the culprit in a variety of neurological diseases, some affecting the myelin sheath. We have used whole exome sequencing in patients with undetermined leukoencephalopathies to uncover the endoplasmic reticulum lipid desaturase DEGS1 as the causative gene in nineteen patients from thirteen unrelated families. Shared features among the cases include severe motor arrest, early nystagmus, dystonia, spasticity and profound failure to thrive. MRI showed hypomyelination, thinning of corpus callosum and progressive thalami and cerebellar atrophy, suggesting a critical role of DEGS1 in myelin development and maintenance. This enzyme converts dihydroceramide (DhCer) into ceramide (Cer) in the final step of the de novo biosynthesis pathway. We detected a marked increase of the substrate DhCer and DhCer/Cer ratios in patient’s fibroblasts and muscle. Further, we used a knockdown approach for disease modelling in Danio rerio, followed by a preclinical test with the first-line treatment for multiple sclerosis, fingolimod (FTY720, Gilenya). The enzymatic inhibition of ceramide synthase, one step prior to DEGS1 in the pathway, by fingolimod, reduced the critical DhCer/Cer imbalance and the severe locomotor disability, increasing the number of myelinating oligodendrocytes in the zebrafish model. These proof-of-concept results pave the way to clinical translation.
Authors
Devesh C. Pant, Imen Dorboz, Agatha Schlüter, Stéphane Fourcade, Nathalie Launay, Javier Joya, Sergio Aguilera-Albesa, Maria Eugenia Yoldi, Carlos Casasnovas, Mary J. Willis, Montserrat Ruiz, Dorothée Ville, Gaetan Lesca, Karine Siquier-Pernet, Isabelle Desguerre, Huifang Yan, Jinming Wang, Margit Burmeister, Lauren Brady, Mark Tarnopolsky, Carles Cornet, Davide Rubbini, Javier Terriente, Kiely N. James, Damir Musaev, Maha S. Zaki, Marc C. Patterson, Brendan C. Lanpher, Eric W. Klee, Filippo Pinto e Vairo, Elizabeth Wohler, Nara Lygia de M. Sobreira, Julie S. Cohen, Reza Maroofian, Hamid Galehdari, Neda Mazaheri, Gholamreza Shariati, Laurence Colleaux, Diana Rodriguez, Joseph G. Gleeson, Cristina Pujades, Ali Fatemi, Odile Boespflug-Tanguy, Aurora Pujol
Citation Information: J Clin Invest. 2019. https://doi.org/10.1172/JCI124159.
Abstract
Background. Sphingolipids are important components of cellular membranes and functionally associated with fundamental processes such as cell differentiation, neuronal signaling and myelin sheath formation. Defects in the synthesis or degradation of sphingolipids leads to various neurological pathologies, however, the entire spectrum of sphingolipid metabolism disorders remained elusive. Methods. A combined approach of genomics and lipidomics was applied to identify and characterize a human sphingolipid metabolism disorder.Results. By whole-exome sequencing in a patient with a multisystem neurological disorder of both the central and peripheral nervous system, we identified a homozygous p.(Ala280Val) variant in DEGS1, which catalyzes the last step in the ceramide synthesis pathway. The blood sphingolipid profile in the patient showed a significant increase in dihydro sphingolipid species which was further recapitulated in patient-derived fibroblasts, in CRISPR/Cas9-derived DEGS1 knockout cells, and by pharmacological inhibition of DEGS1. The enzymatic activity in patient fibroblasts was reduced by 80% compared to wild type cells which was in line with a reduced expression of mutant DEGS1 protein. Moreover, an atypical and potentially neurotoxic sphingosine isomer was identified in patient plasma and in cells expressing mutant DEGS1. Conclusion. We report DEGS1 dysfunction as cause for a novel sphingolipid disorder with hypomyelination and degeneration of both the central and peripheral nervous system.Trial registration. Not applicable.Funding. RESOLVE: Project number 305707; SNF: Project 31003A_153390/1; Rare Disease Initiative Zurich.
Authors
Gergely Karsai, Florian Kraft, Natja Haag, G. Christoph Korenke, Benjamin Hänisch, Alaa Othman, Saranya Suriyanarayanan, Regula Steiner, Cordula Knopp, Michael Mull, Markus Bergmann, J. Michael Schröder, Joachim Weis, Miriam Elbracht, Matthias Begemann, Thorsten Hornemann, Ingo Kurth
Citation Information: J Clin Invest. 2019. https://doi.org/10.1172/JCI122694.
Abstract
The development and function of stem and progenitor cells that produce blood cells are vital in physiology. GATA2 mutations cause GATA-2-deficiency syndrome involving immunodeficiency, myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). GATA-2 physiological activities necessitate that it be strictly regulated, and cell type-specific enhancers fulfill this role. The +9.5 intronic enhancer harbors multiple conserved cis-elements, and germline mutations of these cis-elements are pathogenic in humans. Since mechanisms underlying how GATA2 enhancer disease mutations impact hematopoiesis and pathology are unclear, we generated mouse models of the enhancer mutations. While a multi-motif mutant was embryonic lethal, a single-nucleotide Ets motif mutant was viable, and steady-state hematopoiesis was normal. However, the Ets motif mutation abrogated stem/progenitor cell regeneration following stress. These results reveal a new mechanism in human genetics in which a disease predisposition mutation inactivates enhancer regenerative activity, while sparing developmental activity. Mutational sensitization to stress that instigates hematopoietic failure constitutes a paradigm for GATA-2-deficiency syndrome and other contexts of GATA-2-dependent pathogenesis.
Authors
Alexandra A. Soukup, Ye Zheng, Charu Mehta, Jun Wu, Peng Liu, Miao Cao, Inga Hofmann, Yun Zhou, Jing Zhang, Kirby D. Johnson, Kyunghee Choi, Sunduz Keles, Emery H. Bresnick
Citation Information: J Clin Invest. 2019. https://doi.org/10.1172/JCI123267.
Abstract
Genetic variants at the PTPN2 locus, which encodes the tyrosine phosphatase PTPN2, cause reduced gene expression and are linked to rheumatoid arthritis (RA) and other autoimmune diseases. PTPN2 inhibits signaling through the T cell and cytokine receptors and loss of PTPN2 promotes T cell expansion and CD4 and CD8-driven autoimmunity. However, it remains unknown whether loss of PTPN2 in FoxP3+ regulatory T cells (Treg) plays a role in autoimmunity. Here we aimed to model human autoimmune-predisposing PTPN2 variants, which results in a partial loss of PTPN2 expression, in mouse models of RA. We identified that reduced expression of Ptpn2 enhanced the severity of autoimmune arthritis in the T cell dependent SKG mouse model and demonstrated that this phenotype was mediated through a Treg-intrinsic mechanism. Mechanistically, we found that through dephosphorylation of STAT3, Ptpn2 inhibits IL-6-driven pathogenic loss of FoxP3 after Tregs have acquired RORγt expression, at a stage when chromatin accessibility for STAT3-targeted IL-17 associated transcription factors is maximized. We conclude that PTPN2 promotes FoxP3 stability in mouse RORγt+ Tregs and that loss of function of PTPN2 in Tregs contributes to the association between PTPN2 and autoimmunity.
Authors
Mattias N.D. Svensson, Karen M. Doody, Benjamin J. Schmiedel, Sourya Bhattacharyya, Bharat Panwar, Florian Wiede, Shen Yang, Eugenio Santelli, Dennis J. Wu, Cristiano Sacchetti, Ravindra Gujar, Grégory Seumois, William B. Kiosses, Isabelle Aubry, Gisen Kim, Piotr Mydel, Shimon Sakaguchi, Mitchell Kronenberg, Tony Tiganis, Michel L. Tremblay, Ferhat Ay, Pandurangan Vijayanand, Nunzio Bottini
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI98230.
Abstract
Non-coding RNAs are emerging as important players in gene regulation and disease pathogeneses. Here, we show that a previously uncharacterized long non-coding RNA, NEXN-AS1, modulates the expression of the actin-binding protein NEXN and that NEXN exerts a protective role against atherosclerosis. An expression microarray analysis showed that the expression of both NEXN-AS1 and NEXN were reduced in human atherosclerotic plaques. In vitro experiments revealed that NEXN-AS1 interacted with the chromatin remodeler BAZ1A and the 5′-flanking region of the NEXN gene, and upregulated NEXN expression. Augmentation of NEXN-AS1 expression inhibited toll-like receptor-4 oligomerization and NFκB activity, downregulated the expression of adhesion molecules and inflammatory cytokines by endothelial cells, and suppressed monocyte adhesion to endothelial cells. These inhibitory effects of NEXN-AS1 were abolished by knockdown of NEXN. In vivo experiments of ApoE knockout mice fed a Western high-fat diet demonstrated that NEXN deficiency promoted atherosclerosis and increased macrophage abundance in atherosclerotic lesions, with heightened expression of adhesion molecules and inflammatory cytokines, whereas augmented NEXN expression deterred atherosclerosis. A group of patients with coronary artery disease were found to have lower blood NEXN levels than healthy individuals. These results indicate that NEXN-AS1 and NEXN represent potential therapeutic targets in atherosclerosis related diseases.
Authors
Yan-Wei Hu, Feng-Xia Guo, Yuan-Jun Xu, Pan Li, Zhi-Feng Lu, David G. McVey, Lei Zheng, Qian Wang, John H. Ye, Chun-Min Kang, Shao-Guo Wu, Jing-Jing Zhao, Xin Ma, Zhen Yang, Fu-Chun Fang, Yu-Rong Qiu, Bang-Ming Xu, Lei Xiao, Qian Wu, Li-Mei Wu, Li Ding, Tom R. Webb, Nilesh J. Samani, Shu Ye
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI123319.
PARP inhibition enhances tumor cell-intrinsic immunity in ERCC1-deficient non-small cell lung cancer
Abstract
The cyclic GMP-AMP synthase–stimulator of interferon genes (cGAS/STING) pathway detects cytosolic DNA to activate innate immune responses. Poly(ADP-ribose) polymerase inhibitors (PARPi) selectively target cancer cells with DNA repair deficiencies such as those caused by BRCA1 mutations or ERCC1 defects. Using isogenic cell lines and patient-derived samples, we showed that ERCC1-defective non-small cell lung cancer (NSCLC) cells exhibit an enhanced type I interferon transcriptomic signature, and that low ERCC1 expression correlates with increased lymphocytic infiltration. We demonstrated that clinical PARPi, including olaparib and rucaparib, have cell-autonomous immunomodulatory properties in ERCC1-defective NSCLC and BRCA1-defective triple-negative breast cancer (TNBC) cells. Mechanistically, PARPi generated cytoplasmic chromatin fragments with micronuclei characteristics; these were found to activate cGAS/STING, downstream type I interferon signaling and CCL5 secretion. Importantly, these effects were suppressed in PARP1-null TNBC cells, suggesting that this phenotype resulted from an on-target effect of PARPi on PARP1. PARPi also potentiated interferon-γ-induced PD-L1 expression in NSCLC cell lines and in fresh patient tumor cells; this effect was enhanced in ERCC1-deficient contexts. Our data provide the preclinical rationale for using PARPi as immunomodulatory agents in appropriately molecularly-selected populations.
Authors
Roman M. Chabanon, Gareth Muirhead, Dragomir B. Krastev, Julien Adam, Daphné Morel, Marlène Garrido, Andrew Lamb, Clémence Hénon, Nicolas Dorvault, Mathieu Rouanne, Rebecca Marlow, Ilirjana Bajrami, Marta Llorca Cardeñosa, Asha Konde, Benjamin Besse, Alan Ashworth, Stephen J. Pettitt, Syed Haider, Aurélien Marabelle, Andrew N.J. Tutt, Jean-Charles Soria, Christopher J. Lord, Sophie Postel-Vinay
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI120110.
Abstract
BACKGROUND. Awake neurosurgery requires patients to converse and respond to visual or verbal prompts to identify and protect brain tissue supporting essential functions such as language, primary sensory modalities, and motor function. These procedures can be poorly tolerated due to patient anxiety, yet acute anxiolytic medications typically cause sedation and impair cortical function. METHODS. In this study, direct electrical stimulation of the left dorsal anterior cingulum bundle was discovered to reliably evoke positive affect and anxiolysis without sedation in an epilepsy patient undergoing research testing during standard, in-patient intracranial electrode monitoring. These effects were quantified using subjective and objective behavioral measures, and stimulation was found to evoke robust changes in local and distant neural activity. RESULTS. The index patient ultimately required an awake craniotomy procedure to confirm safe resection margins in the treatment of her epilepsy. During the procedure, cingulum bundle stimulation enhanced positive affect and reduced the patient’s anxiety to the point that intravenous anesthetic/anxiolytic medications were discontinued and cognitive testing was completed. Behavioral responses were subsequently replicated in two patients with anatomically similar electrode placements localized to an approximately 1cm span along the anterior dorsal cingulum bundle above genu of the corpus callosum. CONCLUSIONS. The current study demonstrates a robust anxiolytic response to cingulum bundle stimulation in three epilepsy patients. TRIAL REGISTRATION. The current study was not affiliated with any formal clinical trial. FUNDING. This project was supported by the American Foundation for Suicide Prevention and the National Institutes of Health.
Authors
Kelly R. Bijanki, Joseph R. Manns, Cory S. Inman, Ki Sueng Choi, Sahar Harati, Nigel P. Pedersen, Daniel L. Drane, Allison C. Waters, Rebecca E. Fasano, Helen S. Mayberg, Jon T. Willie
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI122530.
Abstract
Mast cells (MCs) are immune sentinels but whether they also function as antigen-presenting cells (APCs) remains elusive. Using mouse models of MC-deficiency, we report MC-dependent recruitment and activation of multiple T cell subsets to the skin and draining lymph nodes (LNs) during dengue virus (DENV) infection. Newly-recruited and locally-proliferating γδT cells were the first responding T cell subset to MC-driven inflammation and their production of IFN-γ was MC-dependent. MC-γδ T cell conjugates were observed consistently in infected peripheral tissues, suggesting a new role for MCs as non-conventional APCs for γδT cells. MC-dependent γδT cell activation and proliferation during DENV infection required TCR signaling and the non-conventional antigen presentation molecule EPCR on MCs. γδT cells, not previously implicated in DENV host defense, killed infected target dendritic cells and contributed to clearance of DENV in vivo. We believe immune synapse formation between MCs and γδT cells is a novel mechanism to induce specific and protective immunity at sites of viral infection.
Authors
Chinmay Kumar Mantri, Ashley L. St. John
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI121561.
Abstract
Joint pain is the defining symptom of osteoarthritis (OA) but its origin and mechanisms remain unclear. Here, we investigated an unprecedented role of osteoclast-initiated subchondral bone remodeling in sensory innervation for OA pain. We show that osteoclasts secrete NETRIN1 to induce sensory nerve axonal growth in subchondral bone. Reduction of osteoclast formation by knockout of receptor activator of nuclear factor kappa-B ligand (Rankl) in osteocytes inhibited the growth of sensory nerves into subchondral bone, DRG neuron hyperexcitability, and behavioral measures of pain hypersensitivity in OA mice. Moreover, we demonstrated a possible role for NETRIN1 secreted by osteoclasts during aberrant subchondral bone remodeling in inducing sensory innervation and OA pain through its receptor DCC (deleted in colorectal cancer). Importantly, knockout of Netrin1 in tartrate-resistant acid phosphatase (TRAP) positive osteoclasts or knockdown of Dcc reduces OA pain behavior. In particular, inhibition of osteoclast activity by alendronate modifies aberrant subchondral bone remodeling and reduces innervation and pain behavior at the early stage of OA. These results suggest that intervention of the axonal guidance molecules (e.g. NETRIN1) derived from aberrant subchondral bone remodeling may have therapeutic potential for OA pain.
Authors
Shouan Zhu, Jianxi Zhu, Gehua Zhen, Yihe Hu, Senbo An, Yusheng Li, Qin Zheng, Zhiyong Chen, Ya Yang, Mei Wan, Richard Leroy Skolasky, Yong Cao, Tianding Wu, Bo Gao, Mi Yang, Manman Gao, Julia Kuliwaba, Shuangfei Ni, Lei Wang, Chuanlong Wu, David Findlay, Holger K. Eltzschig, Hong Wei Ouyang, Janet Crane, Feng-Quan Zhou, Yun Guan, Xinzhong Dong, Xu Cao
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI123366.
Abstract
Both natural influenza infection and current seasonal influenza vaccines primarily induce neutralising antibody responses against highly diverse epitopes within the “head” of the viral hemagglutinin (HA) protein. There is increasing interest on redirecting immunity towards the more conserved HA-stem or stalk as a means to broaden protective antibody responses. Here we examined HA-stem-specific B cell and T-follicular helper (Tfh) cell responses in the context of influenza infection and immunisation in mouse and monkey models. We found that during infection the stem domain was immunologically subdominant to the head in terms of serum antibody production and antigen-specific B and Tfh responses. Similarly, we found HA-stem immunogens were poorly immunogenic compared to the full-length HA with abolished sialic acid binding activity, with limiting Tfh elicitation a potential constraint to the induction or boosting of anti-stem immunity by vaccination. Finally, we confirm that currently licensed seasonal influenza vaccines can boost pre-existing memory responses against the HA-stem in humans. An increased understanding of the immune dynamics surrounding the HA-stem is essential to inform the design of next-generation influenza vaccines for broad and durable protection.
Authors
Hyon-Xhi Tan, Sinthujan Jegaskanda, Jennifer A. Juno, Robyn Esterbauer, Julius Wong, Hannah G. Kelly, Yi Liu, Danielle Tilmanis, Aeron C. Hurt, Jonathan W. Yewdell, Stephen J. Kent, Adam K. Wheatley
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI120572.
Abstract
ARHGEF1 is a RhoA-specific guanine nucleotide exchange factor expressed in hematopoietic cells. We used whole-exome sequencing to identify compound heterozygous mutations in ARHGEF1, resulting in the loss of ARHGEF1 protein expression in two primary-antibody-deficient siblings presenting with recurrent severe respiratory tract infections and bronchiectasis. Both ARHGEF1-deficient patients showed an abnormal B cell immunophenotype, with a deficiency in marginal-zone and memory B cells and an increased frequency of transitional B cells. Furthermore, the patients’ blood contained immature myeloid cells. Analysis of a mediastinal lymph node from one patient highlighted the small size of the germinal centres and an abnormally high plasma cell content. On the molecular level, T and B lymphocytes from both patients displayed low RhoA activity and low steady-state actin polymerization (even after stimulation of lysophospholipid receptors). As a consequence of disturbed regulation of the RhoA downstream target ROCK, the patients’ lymphocytes failed to efficiently restrain AKT phosphorylation. Enforced ARHGEF1 expression or drug-induced activation of RhoA in patients’ cells corrected the impaired actin polymerization and AKT regulation. Our results indicate that ARHGEF1 activity in human lymphocytes is involved in controlling actin cytoskeleton dynamics, restraining PI3K/AKT signalling, and confining B lymphocytes and myelocytes within their dedicated functional environment.
Authors
Amine Bouafia, Sébastien Lofek, Julie Bruneau, Loïc Chentout, Hicham Lamrini, Amélie Trinquand, Marie-Céline Deau, Lucie Heurtier, Véronique Meignin, Capucine Picard, Elizabeth Macintyre, Olivier Alibeu, Marc Bras, Thierry Jo Molina, Marina Cavazzana, Isabelle André-Schmutz, Anne Durandy, Alain Fischer, Eric Oksenhendler, Sven Kracker
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI122035.
Abstract
Energy stress, such as ischemia, induces mitochondrial damage and death in the heart. Degradation of damaged mitochondria by mitophagy is essential for the maintenance of healthy mitochondria and survival. Here we show that mitophagy during myocardial ischemia was mediated predominantly through autophagy characterized by Rab9-associated autophagosomes, rather than the well-characterized form of autophagy that is dependent upon the Atg-conjugation system and LC3. This form of mitophagy played an essential role in protecting the heart against ischemia and was mediated by a protein complex consisting of Ulk1, Rab9, Rip1 and Drp1. This complex allowed recruitment of trans-Golgi membranes associated with Rab9 to damaged mitochondria through Ser179 phosphorylation of Rab9 by Ulk1 and Ser616 phosphorylation of Drp1 by Rip1. Knock-in of Rab9 (S179A) abolished mitophagy and exacerbated injury in response to myocardial ischemia without affecting conventional autophagy. Mitophagy mediated through the Ulk1-Rab9-Rip1-Drp1 pathway protected the heart against ischemia by maintaining healthy mitochondria.
Authors
Toshiro Saito, Jihoon Nah, Shin-ichi Oka, Risa Mukai, Yoshiya Monden, Yusuhiro Maejima, Yoshiyuki Ikeda, Sebastiano Sciarretta, Tong Liu, Hong Li, Erdene Baljinnyam, Diego Fraidenraich, Luke Fritzky, Peiyong Zhai, Shizuko Ichinose, Mitsuaki Isobe, Chiao-Po Hsu, Mondira Kundu, Junichi Sadoshima
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI120606.
Abstract
Peroxisomes perform essential functions in lipid metabolism, including fatty acid oxidation and plasmalogen synthesis. Here, we describe a role for peroxisomal lipid metabolism in mitochondrial dynamics in brown and beige adipocytes. Adipose tissue peroxisomal biogenesis was induced in response to cold exposure through activation of the thermogenic co-regulator PRDM16. Adipose-specific knockout of the peroxisomal biogenesis factor Pex16 (Pex16-AKO) in mice impaired cold tolerance, decreased energy expenditure, and increased diet-induced obesity. Pex16 deficiency blocked cold-induced mitochondrial fission, decreased mitochondrial copy number, and caused mitochondrial dysfunction. Adipose-specific knockout of the peroxisomal beta-oxidation enzyme acyl CoA oxidase 1 (Acox1-AKO) was not sufficient to affect adiposity, thermogenesis or mitochondrial copy number, but knockdown of the plasmalogen synthetic enzyme glyceronephosphate O-acyltransferase (GNPAT) recapitulated the effects of Pex16 inactivation on mitochondrial morphology and function. Plasmalogens are present in mitochondria and decreased with Pex16 inactivation. Their dietary supplementation increased mitochondrial copy number, improved mitochondrial function, and rescued thermogenesis in Pex16-AKO mice. These findings support a surprising interaction between peroxisomes and mitochondria to regulate mitochondrial dynamics and thermogenesis.
Authors
Hongsuk Park, Anyuan He, Min Tan, Jordan M. Johnson, John M. Dean, Terri A. Pietka, Yali Chen, Xiangyu Zhang, Fong-Fu Hsu, Babak Razani, Katsuhiko Funai, Irfan J. Lodhi
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI122478.
Abstract
The adenomatous polyposis coli (APC) gene plays a pivotal role in the pathogenesis of colorectal carcinoma (CRC), but remains a challenge for drug development. Long non-coding RNAs (lncRNAs) are invaluable in identifying cancer pathologies, and providing therapeutic options for cancer patients. Here, we identified a lncRNA (lncRNA-APC1) activated by APC through lncRNA microarray screening, and examined its expression among a large cohort of CRC tissues. A decrease in lncRNA-APC1 expression was positively associated with lymph node and/or distant metastasis, a more advanced clinical stage, as well as a poor prognosis of CRC patients. Additionally, APC can enhance lncRNA-APC1 expression by suppressing the enrichment of PPARα on the lncRNA-APC1 promoter. Furthermore, enforced lncRNA-APC1 expression was sufficient to inhibit CRC cell growth, metastasis and tumor angiogenesis by suppressing exosome production through directly binding Rab5b mRNA and reducing its stability. Importantly, exosomes derived from lncRNA-APC1-silenced CRC cells promoted angiogenesis by activating the MAPK pathway in endothelial cells, and moreover, exosomal Wnt1 largely enhanced CRC cell proliferation and migration through non-canonicial Wnt signaling. Collectively, lncRNA-APC1 is a critical lncRNA regulated by APC in the pathogenesis of CRC. Our findings suggest an APC-regulated lncRNA-APC1 program as an exploitable therapeutic maneuver for CRC patients.
Authors
Feng-Wei Wang, Chen-Hui Cao, Kai Han, Yong-Xiang Zhao, Mu-Yan Cai, Zhi-Cheng Xiang, Jia-Xing Zhang, Jie-Wei Chen, Li-Ping Zhong, Yong Huang, Su-Fang Zhou, Xiao-Han Jin, Xin-Yuan Guan, Rui-Hua Xu, Dan Xie
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI124473.
Abstract
BACKGROUND. Varicella-zoster virus (VZV) is under consideration as a promising recombinant viral vector to deliver foreign antigens including HIV. However, new vectors have come under increased scrutiny since vaccination with Ad5-vectored HIV vaccine trials demonstrated increased HIV risk in individuals with pre-immunity to the vector which was thought to be associated with mucosal immune activation (IA). Therefore, defining the impact of VZV vaccination on IA is particularly important with the prospect of developing an HIV/VZV chimeric vaccine. METHODS. VZV-seropositive healthy Kenyan women (n=44) were immunized with high dose live-attenuated VZV vaccine, and the expression of IA markers including CD38 and HLA-DR on CD4 T cells isolated from blood, cervix and rectum, markers of cell migration and tissue retention and the concentration of genital and intestinal cytokines were assessed. A delayed group (n=22) was used to control for natural variations in these parameters. RESULTS. Although immunogenic, VZV vaccination did not result in significant difference in the frequency of cervical activated (HLA-DR+CD38+) CD4 T cells (median 1.61%, IQR 0.93%-2.76%) at 12 weeks post-vaccination when compared to baseline (median 1.58%, IQR 0.75%-3.04%), the primary outcome for this study. VZV vaccination also had no measurable effect on any of the IA parameters at 4, 8 and 12 weeks post-vaccination. CONCLUSION. This study provides the first-ever evidence about the effects of VZV-vaccination on human mucosal IA status and supports further evaluation of VZV as a potential vector in an HIV vaccine. TRIAL REGISTRATION. ClinicalTrials.gov NCT02514018. FUNDING. Primary support from CIHR. For others see below.
Authors
Catia T. Perciani, Bashir Farah, Rupert Kaul, Mario A. Ostrowski, Salaheddin M. Mahmud, Omu Anzala, Walter Jaoko, Kelly S. MacDonald
Citation Information: J Clin Invest. 2018. https://doi.org/10.1172/JCI122367.
Abstract
Prostate cancer (PCa) progressed to castration resistance (CRPC) is a fatal disease. CRPC tumors develop resistance to new-generation anti-androgen enzalutamide through lineage plasticity, characterized by epithelial-mesenchymal transition (EMT) and basal-like phenotype. FOXA1 is a transcription factor essential for epithelial lineage differentiation. Here, we demonstrate that FOXA1 loss leads to remarkable up-regulation of transforming growth factor beta 3 (TGFB3), which encodes a ligand of TGF-β pathway. Mechanistically, this is due to genomic occupancy of FOXA1 on an upstream enhancer of TGFB3 gene to directly inhibit its transcription. Functionally, FOXA1 down-regulation induces TGF-β signaling, EMT, and cell motility, which is effectively blocked by TGF-β receptor I inhibitor Galunisertib (LY2157299). Tissue microarray analysis confirmed reduced levels of FOXA1 protein and a concordant increase in TGF-β signaling, indicated by SMAD2 phosphorylation, in CRPC as compared to primary tumors. Importantly, combinatorial LY2157299 treatment sensitized PCa cells to enzalutamide, leading to synergistic effects in inhibiting cell invasion in vitro and xenograft CRPC tumor growth and metastasis in vivo. Therefore, our study establishes FOXA1 as an important regulator of lineage plasticity mediated in part by TGF-β signaling and supports a novel therapeutic strategy to control lineage switching and potentially extend clinical response to antiandrogen therapies.
Authors
Bing Song, Su-Hong Park, Jonathan C. Zhao, Ka-wing Fong, Shangze Li, Yongik Lee, Yeqing A. Yang, Subhasree Sridhar, Xiaodong Lu, Sarki A. Abdulkadir, Robert L. Vessella, Colm Morrissey, Timothy M. Kuzel, William J. Catalona, Ximing J. Yang, Jindan Yu
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ISSN: 0021-9738 (print), 1558-8238 (online)