Neuron-oligodendrocyte potassium shuttling at nodes of Ranvier protects against inflammatory demyelination

• Text
• PDF

Abstract

Multiple sclerosis (MS) is a progressive inflammatory-demyelinating disease of the central nervous system. Increasing evidence suggests that vulnerable neurons in MS exhibit fatal metabolic exhaustion over time, a phenomenon hypothesized to be caused by chronic hyperexcitability. Axonal Kv7 (outward rectifying) and oligodendroglial Kir4.1 (inward rectifying) potassium channels have important roles in regulating neuronal excitability at and around nodes of Ranvier. Here, we studied the spatial and functional relationship between neuronal Kv7 and oligodendroglial Kir4.1 channels and assessed the transcriptional and functional signatures of cortical and retinal projection neurons under physiological and inflammatory-demyelinating conditions. We found that both channels became dysregulated in MS and experimental autoimmune encephalomyelitis (EAE) with Kir4.1 channels being chronically downregulated and Kv7 channel subunits being transiently upregulated during inflammatory demyelination. Further, we observed that pharmacological Kv7 channel opening with retigabine reduced neuronal hyperexcitability in human and EAE neurons, improved clinical EAE signs and rescued neuronal pathology in oligodendrocyte-Kir4.1-deficient mice. In summary, our findings indicate that neuron-oligodendrocyte compensatory interactions promote resilience through Kv7 and Kir4.1 channels and suggest pharmacological activation of nodal Kv7 channels as a neuroprotective strategy against inflammatory demyelination.

Authors

Hannah Kapell, Luca Fazio, Julia Dyckow, Sophia Schwarz, Andrés Cruz-Herranz, Christina Mayer, Joaquin Campos, Elisa D´Este, Wiebke Möbius, Christian Cordano, Anne-Katrin Pröbstel, Marjan Gharagozloo, Amel Zulji, Venu Narayanan Naik, Anna-Katharina Delank, Manuela Cerina, Thomas Müntefering, Celia Lerma-Martin, Jana K. Sonner, Jung H. Sin, Paul Disse, Nicole Rychlik, Khalida Sabeur, Manideep Chavali, Rajneesh Srivastava, Matthias Heidenreich, Kathryn C. Fitzgerald, Guiscard Seebohm, Christine Stadelmann, Bernhard Hemmer, Michael Platten, Thomas J. Jentsch, Maren Engelhardt, Thomas Budde, Klaus-Armin Nave, Peter A. Calabresi, Manuel A. Friese, Ari J. Green, Claudio Acuna, David H. Rowitch, Sven G. Meuth, Lucas Schirmer

Asparagine protects pericentral hepatocytes during acute liver injury

• Text
• PDF

Abstract

The non-essential amino acid asparagine can only be synthesized de novo by the enzymatic activity of asparagine synthetase (ASNS). While ASNS and asparagine have been implicated in the response to numerous metabolic stressors in cultured cells, the in vivo relevance of this enzyme in stress-related pathways remains unexplored. Here, we found ASNS to be expressed in pericentral hepatocytes, a population of hepatic cells specialized in xenobiotic detoxification. ASNS expression was strongly enhanced in two models of acute liver injury: carbon tetrachloride (CCl4) and acetaminophen (APAP). We found that mice with hepatocyte-specific Asns deletion (Asnshep-/-) were more prone to pericentral liver damage than their control (Asnshep+/+) littermates after toxin exposure. This phenotype could be reverted by intravenous administration of asparagine. Unexpectedly, the stress-induced upregulation of ASNS involved an ATF4-independent, non-canonical pathway mediated by the nuclear receptor, liver receptor homolog 1 (LRH-1; NR5A2). Altogether, our data indicate that the induction of the asparagine-producing enzyme ASNS acts as an adaptive mechanism to constrain the necrotic wave that follows toxin administration and provide proof of concept that intravenous delivery of asparagine can dampen hepatotoxin-induced pericentral hepatocellular death.

Authors

Yu Sun, Hadrien Demagny, Adrien Faure, Francesca Pontanari, Antoine Jalil, Nadia Bresciani, Ece Yildiz, Melanie Korbelius, Alessia Perino, Kristina Schoonjans

YAP1 and WWTR1 expression inversely correlate with neuroendocrine markers in Merkel cell carcinoma

• Text
• PDF

Abstract

BACKGROUND. Merkel cell carcinoma (MCC) is an aggressive neuroendocrine (NE) skin cancer caused by severe UV-induced mutations or expression of Merkel cell polyomavirus (MCPyV) large and small T antigens (LT and ST). Despite deep genetic differences between MCPyV-positive and -negative subtypes, current clinical diagnostic markers are indistinguishable between subtypes and the expression profile of MCC tumors is unexplored. METHODS. Here we leveraged bulk and single-cell RNA sequencing of patient-derived tumor biopsies and cell lines to explore the underlying transcriptional diversity of MCC. RESULTS. Strikingly, MCC samples could be separated into transcriptional subtypes that were independent of MCPyV status. Instead, we observed an inverse correlation between a NE gene signature and the Hippo pathway transcription factors Yes1-associated transcriptional regulator (YAP1) and WW domain containing transcriptional regulator (WWTR1). This inverse correlation was present at the transcript and protein levels in the tumor biopsies as well as in established and patient-derived cell lines. Mechanistically, expression of YAP1 or WWTR1 in a MCPyV-positive MCC cell line induced cell-cycle arrest at least in part through TEAD-dependent transcriptional repression of MCPyV LT. CONCLUSION. These findings describe previously unrecognized heterogeneity in NE gene expression within MCC and support the model that YAP1/WWTR1 silencing is essential for the development of MCPyV-positive MCC. FUNDING. US Public Health Service grants R35CA232128, P01CA203655, and P30CA06516.

Authors

Thomas C. Frost, Ashley K. Gartin, Mofei Liu, Jingwei Cheng, Harita Dharaneeswaran, Derin B. Keskin, Catherine J. Wu, Anita Giobbie-Hurder, Manisha Thakuria, James A. DeCaprio

Single-cell characterization of anti-LAG3+anti-PD1 treatment in melanoma patients

• Text
• PDF

Abstract

BACKGROUND. Relatlimab+nivolumab (anti-LAG3+anti-PD1) has been approved by FDA as a 1st-line therapy in stage III/IV melanoma, but its detailed effect on the immune system is unknown. METHODS. We evaluated blood samples from 40 immunotherapy-naïve or prior immunotherapy-refractory patients with metastatic melanoma treated with anti-LAG3+anti-PD1 in a phase I trial (NCT01968109) using single-cell RNA and T cell receptor (TCR) sequencing (scRNA+TCRαβ-seq) combined with other multiomics profiling. RESULTS. The highest LAG3 expression was noted in NK cells, regulatory T cells (Tregs), and CD8+ T cells, and these cell populations underwent the most significant changes during the treatment. Adaptive NK cells were enriched in responders and underwent profound transcriptomic changes during the therapy resulting in an active phenotype. LAG3+ Tregs expanded but based on the transcriptome profile became metabolically silent during the treatment. Lastly, higher baseline TCR clonality was observed in responding patients, and their expanding CD8+ T cell clones gained more cytotoxic and NK-like phenotype. CONCLUSION. Anti-LAG3+anti-PD1 therapy has profound effects on NK cells and Tregs in addition to CD8+ T cells. TRIAL REGISTRATION. ClinicalTrials.gov (NCT01968109) FUNDING. Cancer Foundation Finland, Sigrid Juselius Foundation, Signe and Ane Gyllenberg Foundation, Relander Foundation, State funding for university-level health research in Finland, a Helsinki Institute of Life Sciences Fellow grant, Academy of Finland, and an investigator-initiated research grant from BMS.

Authors

Jani Huuhtanen, Henna H.E. Kasanen, Katriina Peltola, Tapio Lönnberg, Virpi Glumoff, Oscar Brück, Olli Dufva, Karita Peltonen, Johanna Vikkula, Emmi Jokinen, Mette Ilander, Moon Hee Lee, Siru Mäkelä, Marta Nyakas, Bin Li, Micaela Hernberg, Petri Bono, Harri Lähdesmäki, Anna Kreutzman, Satu Mustjoki

Targeting pleckstrin-2-Akt signaling reduces proliferation in myeloproliferative neoplasm models

• Text
• PDF

Abstract

Myeloproliferative neoplasms (MPNs) are characterized by the activated JAK2-STAT pathway. Pleckstrin-2 (Plek2) is a downstream target of the JAK2-STAT pathway and overexpressed in patients with MPNs. We previously revealed that Plek2 plays critical roles in the pathogenesis of JAK2 mutated MPNs. The non-essential roles of Plek2 under physiologic conditions makes it an ideal target for MPN therapy. Here we identified first-in-class Plek2 inhibitors through an in silico high-throughput screening and cell-based assays followed by the synthesis of analogs. The Plek2 specific small molecule inhibitors showed potent inhibitory effects on cell proliferation. Mechanistically, Plek2 interacts with and enhances the activity of Akt through the recruitment of downstream effector proteins. The Plek2 signaling complex also includes Hsp72 that protects Akt from degradation. These functions were blocked by Plek2 inhibitors via their direct binding to Plek2 DEP domain. The role of Plek2 in activating the Akt signaling was further confirmed in vivo using a hematopoietic specific Pten knockout mouse model. We next tested Plek2 inhibitors alone or in combination with an Akt inhibitor in various MPN mouse models, which showed significant therapeutic efficacies similar to the genetic depletion of Plek2. The Plek2 inhibitor was also effective in reducing proliferation of CD34 positive cells from MPN patients. Our studies reveal a Plek2-Akt complex that drives cell proliferation and can be targeted by a new class of anti-proliferative compounds for MPN therapy.

Authors

Xu Han, Yang Mei, Rama K. Mishra, Honghao Bi, Atul D. Jain, Gary E. Schiltz, Baobing Zhao, Madina Sukhanova, Pan Wang, Arabela A. Grigorescu, Patricia C. Weber, John J. Piwinski, Miguel A. Prado, Joao A. Paulo, Len Stephens, Karen E. Anderson, Charles S. Abrams, Jing Yang, Peng Ji

Antigen specificity and cross-reactivity drive functionally diverse anti-Aspergillus fumigatus T cell responses in cystic fibrosis

• Text
• PDF

Abstract

BACKGROUND. The fungus Aspergillus fumigatus causes a variety of clinical phenotypes in patients with cystic fibrosis (pwCF). T-helper (Th) cells orchestrate immune responses against fungi, but the types of A. fumigatus-specific Th-cells in pwCF and their contribution to protective immunity or inflammation remain poorly characterized. METHODS. We used antigen-reactive T cell enrichment (ARTE) to investigate fungus-reactive Th cells in peripheral blood of pwCF and healthy controls. RESULTS. We show that clonally expanded, high-avidity A. fumigatus-specific effector Th-cells develop in pwCF, which are absent in healthy donors. Individual patients were characterized by distinct Th1, Th2, or Th17 dominated responses that remained stable over years. These different Th subsets target different A. fumigatus proteins, indicating that differential antigen uptake and presentation directs Th-cell subset development. Patients with allergic bronchopulmonary aspergillosis (ABPA) are characterized by high frequencies of Th2-cells that cross-recognize various filamentous fungi. CONCLUSION. Our data highlight the development of heterogenous Th responses targeting different protein fractions of a single fungal pathogen and identify the development of multispecies cross-reactive Th2-cells as a potential risk factor for ABPA. FUNDING. This research was supported by grants from the German Research Foundation (DFG) under Germany’s Excellence Strategy - EXC 2167-390884018 “Precision Medicine in Chronic Inflammation”, EXC 2051-390713860 “Balance of the Microverse”; the Oskar Helene Heim Stiftung; the Christiane Herzog Stiftung, Stuttgart, Germany; the Mukoviszidose Institut gGmbH, Bonn, the research and development arm of the German Cystic Fibrosis Association Mukoviszidose e.V; the German Federal Ministry of Education and Science (BMBF) InfectControl 2020 Projects AnDiPath, BMBF 03ZZ0838A+B.

Authors

Carsten Schwarz, Patience Eschenhagen, Henrijette Schmidt, Thordis Hohnstein, Christina Iwert, Claudia Grehn, Jobst Roehmel, Eva Steinke, Mirjam Stahl, Laura Lozza, Ekaterina Tikhonova, Elisa Rosati, Ulrik Stervbo, Nina Babel, Jochen G. Mainz, Hilmar Wisplinghoff, Frank Ebel, Lei-Jie Jia, Matthew G. Blango, Peter Hortschansky, Sascha Brunke, Bernhard Hube, Axel A. Brakhage, Olaf Kniemeyer, Alexander Scheffold, Petra Bacher

Th2-skewed T cells correlate with B cell response to α-Gal and tick antigens in α-Gal syndrome

• Text
• PDF

Abstract

Tick bites have been shown to transmit a novel form of severe food allergy, the galactose-α-1,3-galactose (α-Gal) syndrome (AGS). Cellular responses to α-Gal in AGS patients have to date not been thoroughly scrutinized. Therefore, we investigated T and B cell proliferation, activation and cytokine profiles in response to tick protein extract (TE) and α-Gal-free TE in AGS patients and healthy controls. T and B cells from both patients and controls proliferated in response to TE, but significantly more in the patients. B cell proliferation, but not T cell proliferation, in AGS patients was reduced by removing α-Gal from the TE. In addition, TE induced a clear Th2 cytokine profile in AGS patients. Expression of CD23 by B cells correlated only to T cell proliferation. However, both B cell proliferation and CD23 expression were reduced when CD40L and IL-4 were blocked. A large proportion of the IgG1 and IgE antibodies binding TE in AGS patients were directed against the α-Gal epitope. We have for the first time investigated T and B cell responses to α-Gal carrying tick proteins in AGS patients, which will be essential for the understanding of the immune response against an allergenic carbohydrate transmitted by ticks.

Authors

Danijela Apostolovic, Jeanette Grundström, Mensiena B. Gea Kiewiet, Marija Perusko, Carl Hamsten, Maria H. Starkhammar, Staffan Paulie, Marianne van Hage

A TRPV4-dependent neuro-immune axis in the spinal cord promotes neuropathic pain

• Text
• PDF

Abstract

Microglia, resident macrophages of the central nervous system (CNS), are essential to brain development, homeostasis, and disease. Microglial activation and proliferation are hallmarks of many CNS diseases including neuropathic pain. However, molecular mechanisms that govern the spinal neuro-immune axis in the setting of neuropathic pain remain incompletely understood. Here we show that genetic ablation or pharmacological blockade of transient receptor potential vanilloid type 4 (TRPV4) markedly attenuated neuropathic pain-like behaviors in a mouse model of spared nerve injury. Mechanistically, microglia-expressed TRPV4 mediated microglial activation and proliferation and promoted functional and structural plasticity of excitatory spinal neurons through releasing lipocalin-2. Our results suggest that microglial TRPV4 channels reside at the center of the neuro-immune axis in the spinal cord that transforms peripheral nerve injury into central sensitization and neuropathic pain, thereby identifying TRPV4 as a promising new target for the treatment of chronic pain.

Authors

Xueming Hu, Lixia Du, Shenbin Liu, Zhou Lan, Kaikai Zang, Jing Feng, Yonghui Zhao, Xingliang Yang, Zili Xie, Peter L. Wang, Aaron M. Ver Heul, Lvyi Chen, Vijay K. Samineni, Yan-Qing Wang, Kory J. Lavine, Robert W. Gereau, Gregory F. Wu, Hongzhen Hu

Pre-clinical and clinical evidence for suppression of alcohol intake by apremilast

• Text
• PDF

Abstract

Treatment options for Alcohol Use Disorders (AUD) have minimally advanced since 2004, while the annual deaths and economic toll have increased alarmingly. Phosphodiesterase type 4 (PDE4) is associated with alcohol and nicotine dependence. PDE4 inhibitors were identified as a potential AUD treatment using a novel bioinformatics approach. We prioritized a newer PDE4 inhibitor, apremilast, as ideal for repurposing, (i.e. FDA approved for psoriasis, low incidence of adverse events, excellent safety profile), and tested it using multiple animal strains and models, as well as in a human Phase IIa study. We found that apremilast reduced binge-like alcohol intake and behavioral measures of alcohol motivation in mouse models of genetic risk for drinking to intoxication. Apremilast also reduced excessive alcohol drinking in models for stress-facilitated drinking and alcohol dependence. Using site-directed drug infusions and electrophysiology, we uncovered that apremilast may act to lessen drinking in mice by increasing neural activity in the nucleus accumbens, a key brain region in the regulation of alcohol intake. Importantly, apremilast (90 mg/d) reduced excessive drinking in non-treatment seeking individuals with AUD in a double blind, placebo-controlled study. These results demonstrate that apremilast suppresses excessive alcohol drinking across the spectrum of AUD severity.

Authors

Kolter B. Grigsby, Regina A. Mangieri, Amanda J. Roberts, Marcelo F. Lopez, Evan J. Firsick, Kayla G. Townsley, Alan Beneze, Jessica Bess, Toby K. Eisenstein, Joseph J. Meissler, John M. Light, Jenny Miller, Susan Quello, Farhad Shadan, Michael H. Skinner, Heather C. Aziz, Pamela Metten, Richard A. Morissett, John C. Crabbe, Marisa Roberto, Howard C. Becker, Barbara J. Mason, Angela R. Ozburn

Type 2 diabetes candidate genes, including PAX5, cause impaired insulin secretion in human pancreatic islets

• Text
• PDF

Abstract

Type 2 diabetes (T2D) is caused by insufficient insulin secretion from pancreatic β-cells. To identify candidates contributing to T2D pathophysiology, we studied human pancreatic islets from ~300 individuals. We found 395 differentially expressed genes (DEGs) in islets from individuals with T2D, including, to our knowledge, novel (OPRD1, PAX5, TET1) and previously identified (CHL1, GLRA1, IAPP) candidates. A third of the identified islet expression changes may predispose to diabetes, as they associated with HbA1c in individuals not previously diagnosed with T2D. Most DEGs were expressed in human β-cells based on single-cell RNA-sequencing data. Additionally, DEGs displayed alterations in open chromatin and associated with T2D-SNPs. Mouse knock-out strains demonstrated that T2D-associated candidates regulate glucose homeostasis and body composition in vivo. Functional validation showed that mimicking T2D-associated changes for OPRD1, PAX5, and SLC2A2 impaired insulin secretion. Impairments in Pax5-overexpressing β-cells were due to severe mitochondrial dysfunction. Finally, we discovered PAX5 as a potential transcriptional regulator of many T2D-associated DEGs in human islets. Overall, we identified molecular alterations in human pancreatic islets contributing to β-cell dysfunction in T2D pathophysiology.

Authors

Karl Bacos, Alexander Perfilyev, Alexandros Karagiannopoulos, Elaine Cowan, Jones K. Ofori, Ludivine Bertonnier-Brouty, Tina Rönn, Andreas Lindqvist, Cheng Luan, Sabrina Ruhrmann, Mtakai Ngara, Åsa Nilsson, Sevda Gheibi, Claire L. Lyons, Jens O. Lagerstedt, Mohammad Barghouth, Jonathan L.S. Esguerra, Petr Volkov, Malin Fex, Hindrik Mulder, Nils Wierup, Ulrika Krus, Isabella Artner, Lena Eliasson, Rashmi B. Prasad, Luis Rodrigo Cataldo, Charlotte Ling