Issue published April 8, 2021

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Delta-like 4 is required for pulmonary vascular arborization and alveolarization in the developing lung

In this issue, Xia et al. explore the role of delta-like 4 (DLL4), an endothelial cell Notch ligand, in the regulation of lung microvascularization and distal lung morphogenesis. Using lung mapping approaches in mouse and human cadaveric samples, as well functional studies in Dll4+/– mice, they show that DLL4 is required for pulmonary microvascularization and alveolarization during lung development. The cover image shows a postnatal day 6 lung sample from a Dll4+/lacZ reporter mouse stained with X-gal (blue) and platelet endothelial cell adhesion molecule (PECAM, brown) and counterstained with Nuclear Fast Red.

Research Articles
Abstract

Virus-induced respiratory tract infections are a major health burden in childhood, and available treatments are supportive rather than disease modifying. Rhinoviruses (RVs), the cause of approximately 80% of common colds, are detected in nearly half of all infants with bronchiolitis and the majority of children with an asthma exacerbation. Bronchiolitis in early life is a strong risk factor for the development of asthma. Here, we found that RV infection induced the expression of miRNA 122 (miR-122) in mouse lungs and in human airway epithelial cells. In vivo inhibition specifically in the lung reduced neutrophilic inflammation and CXCL2 expression, boosted innate IFN responses, and ameliorated airway hyperreactivity in the absence and in the presence of allergic lung inflammation. Inhibition of miR-122 in the lung increased the levels of suppressor of cytokine signaling 1 (SOCS1), which is an in vitro–validated target of miR-122. Importantly, gene silencing of SOCS1 in vivo completely reversed the protective effects of miR-122 inhibition on RV-induced lung disease. Higher miR-122 expression in nasopharyngeal aspirates was associated with a longer time on oxygen therapy and a higher rate of treatment failure in 87 infants hospitalized with moderately severe bronchiolitis. These results suggest that miR-122 promotes RV-induced lung disease via suppression of its target SOCS1 in vivo. Higher miR-122 expression was associated with worse clinical outcomes, highlighting the potential use of anti-miR-122 oligonucleotides, successfully trialed for treatment of hepatitis C, as potential therapeutics for RV-induced bronchiolitis and asthma exacerbations.

Authors

Adam M. Collison, Leon A. Sokulsky, Elizabeth Kepreotes, Ana Pereira de Siqueira, Matthew Morten, Michael R. Edwards, Ross P. Walton, Nathan W. Bartlett, Ming Yang, Thi Hiep Nguyen, Sebastian L. Johnston, Paul S. Foster, Joerg Mattes

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Abstract

The molecular mechanisms by which endothelial cells (ECs) regulate pulmonary vascularization and contribute to alveolar epithelial cell development during lung morphogenesis remain unknown. We tested the hypothesis that delta-like 4 (DLL4), an EC Notch ligand, is critical for alveolarization by combining lung mapping and functional studies in human tissue and DLL4-haploinsufficient mice (Dll4+/lacz). DLL4 expressed in a PECAM-restricted manner in capillaries, arteries, and the alveolar septum from the canalicular to alveolar stage in mice and humans. Dll4 haploinsufficiency resulted in exuberant, nondirectional vascular patterning at E17.5 and P6, followed by smaller capillaries and fewer intermediate blood vessels at P14. Vascular defects coincided with polarization of lung EC expression toward JAG1-NICD-HES1 signature and decreased tip cell-like (Car4) markers. Dll4+/lacZ mice had impaired terminal bronchiole development at the canalicular stage and impaired alveolarization upon lung maturity. We discovered that alveolar type I cell (Aqp5) markers progressively decreased in Dll4+/lacZ mice after birth. Moreover, in human lung EC, DLL4 deficiency programmed a hypersprouting angiogenic phenotype cell autonomously. In conclusion, DLL4 is expressed from the canalicular to alveolar stage in mice and humans, and Dll4 haploinsufficiency programs dysmorphic microvascularization, impairing alveolarization. Our study reveals an obligate role for DLL4-regulated angiogenesis in distal lung morphogenesis.

Authors

Sheng Xia, Heather L. Menden, Nick Townley, Sherry M. Mabry, Jeffrey Johnston, Michael F. Nyp, Daniel P. Heruth, Thomas Korfhagen, Venkatesh Sampath

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Abstract

ORM1-like 3 (ORMDL3) has strong genetic linkage to childhood onset asthma. To determine whether ORMDL3 selective expression in airway smooth muscle (ASM) influences ASM function, we used Cre-loxP techniques to generate transgenic mice (hORMDL3Myh11eGFP-cre), which express human ORMDL3 selectively in smooth muscle cells. In vitro studies of ASM cells isolated from the bronchi of hORMDL3Myh11eGFP-cre mice demonstrated that they developed hypertrophy (quantitated by FACS and image analysis), developed hyperplasia (assessed by BrdU incorporation), and expressed increased levels of tropomysin proteins TPM1 and TPM4. siRNA knockdown of TPM1 or TPM4 demonstrated their importance to ORMDL3-mediated ASM proliferation but not hypertrophy. In addition, ASM derived from hORMDL3Myh11eGFP-cre mice had increased contractility to histamine in vitro, which was associated with increased levels of intracellular Ca2+; increased cell surface membrane Orai1 Ca2+ channels, which mediate influx of Ca2+ into the cytoplasm; and increased expression of ASM contractile genes sarco/endoplasmic reticulum Ca2+ ATPase 2b and smooth muscle 22. In vivo studies of hORMDL3Myh11eGFP-cre mice demonstrated that they had a spontaneous increase in ASM and airway hyperreactivity (AHR). ORMDL3 expression in ASM thus induces changes in ASM (hypertrophy, hyperplasia, increased contractility), which may explain the contribution of ORMDL3 to the development of AHR in childhood onset asthma, which is highly linked to ORMDL3 on chromosome 17q12-21.

Authors

Alexa K. Pham, Marina Miller, Peter Rosenthal, Sudipta Das, Ning Weng, Sunghoon Jang, Richard C. Kurten, Jana Badrani, Taylor A. Doherty, Brian Oliver, David H. Broide

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Abstract

Lung cancer with oncogenic KRAS makes up a significant proportion of lung cancers and is accompanied by a poor prognosis. Recent advances in understanding the molecular pathogenesis of lung cancer with oncogenic KRAS have enabled the development of drugs, yet mutated KRAS remains undruggable. We performed small-molecule library screening and identified verteporfin, a yes-associated protein 1 (YAP1) inhibitor; verteporfin treatment markedly reduced cell viability in KRAS-mutant lung cancer cells in vitro and suppressed KRAS-driven lung tumorigenesis in vivo. Comparative functional analysis of verteporfin treatment and YAP1 knockdown with siRNA revealed that the cytotoxic effect of verteporfin was at least partially independent of YAP1 inhibition. A whole-transcriptome approach revealed the distinct expression profiles in KRAS-mutant lung cancer cells between verteporfin treatment and YAP1 knockdown and identified the selective involvement of the ER stress pathway in the effects of verteporfin treatment in KRAS-mutant lung cancer, leading to apoptotic cell death. These data provide novel insight to uncover vulnerabilities in KRAS-driven lung tumorigenesis.

Authors

Iwao Shimomura, Naoaki Watanabe, Tomofumi Yamamoto, Minami Kumazaki, Yuji Tada, Koichiro Tatsumi, Takahiro Ochiya, Yusuke Yamamoto

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Abstract

No effective systemic treatment is available for patients with unresectable, recurrent, or metastatic mucoepidermoid carcinoma (MEC), the most common salivary gland malignancy. MEC is frequently associated with a t(11;19)(q14-21;p12-13) translocation that creates a CRTC1-MAML2 fusion gene. The CRTC1-MAML2 fusion exhibited transforming activity in vitro; however, whether it serves as an oncogenic driver for MEC establishment and maintenance in vivo remains unknown. Here, we show that doxycycline-induced CRTC1-MAML2 knockdown blocked the growth of established MEC xenografts, validating CRTC1-MAML2 as a therapeutic target. We further generated a conditional transgenic mouse model and observed that Cre-induced CRTC1-MAML2 expression caused 100% penetrant formation of salivary gland tumors resembling histological and molecular characteristics of human MEC. Molecular analysis of MEC tumors revealed altered p16-CDK4/6-RB pathway activity as a potential cooperating event in promoting CRTC1-MAML2–induced tumorigenesis. Cotargeting of aberrant p16-CDK4/6-RB signaling and CRTC1-MAML2 fusion–activated AREG/EGFR signaling with the respective CDK4/6 inhibitor Palbociclib and EGFR inhibitor Erlotinib produced enhanced antitumor responses in vitro and in vivo. Collectively, this study provides direct evidence for CRTC1-MAML2 as a key driver for MEC development and maintenance and identifies a potentially novel combination therapy with FDA-approved EGFR and CDK4/6 inhibitors as a potential viable strategy for patients with MEC.

Authors

Zirong Chen, Wei Ni, Jian-Liang Li, Shuibin Lin, Xin Zhou, Yuping Sun, Jennifer W. Li, Marino E. Leon, Maria D. Hurtado, Sergei Zolotukhin, Chen Liu, Jianrong Lu, James D. Griffin, Frederic J. Kaye, Lizi Wu

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Abstract

Proline-glycine-proline (PGP) and its acetylated form (Ac-PGP) are neutrophil chemoattractants generated by collagen degradation, and they have been shown to play a role in chronic inflammatory disease. However, the mechanism for matrikine regulation in acute inflammation has not been well established. Here, we show that these peptides are actively transported from the lung by the oligopeptide transporter, PEPT2. Following intratracheal instillation of Ac-PGP in a mouse model, there was a rapid decline in concentration of the labeled peptide in the bronchoalveolar lavage (BAL) over time and redistribution to extrapulmonary sites. In vitro knockdown of the PEPT2 transporter in airway epithelia or use of a competitive inhibitor of PEPT2, cefadroxil, significantly reduced uptake of Ac-PGP. Animals that received intratracheal Ac-PGP plus cefadroxil had higher levels of Ac-PGP in BAL and lung tissue. Utilizing an acute LPS-induced lung injury model, we demonstrate that PEPT2 blockade enhanced pulmonary Ac-PGP levels and lung inflammation. We further validated this effect using clinical samples from patients with acute lung injury in coculture with airway epithelia. This is the first study to our knowledge to determine the in vitro and in vivo significance of active matrikine transport as a mechanism of modulating acute inflammation and to demonstrate that it may serve as a potential therapeutic target.

Authors

Sarah W. Robison, JinDong Li, Liliana Viera, Jonathan P. Blackburn, Rakesh P. Patel, J. Edwin Blalock, Amit Gaggar, Xin Xu

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Abstract

The increased incidence of whooping cough worldwide suggests that current vaccination against Bordetella pertussis infection has limitations in quality and duration of protection. The resurgence of infection has been linked to the introduction of acellular vaccines (aP), which have an improved safety profile compared with the previously used whole-cell (wP) vaccines. To determine immunological differences between aP and wP priming in infancy, we performed a systems approach of the immune response to booster vaccination. Transcriptomic, proteomic, cytometric, and serologic profiling revealed multiple shared immune responses with different kinetics across cohorts, including an increase of blood monocyte frequencies and strong antigen-specific IgG responses. Additionally, we found a prominent subset of aP-primed individuals (30%) with a strong differential signature, including higher levels of expression for CCL3, NFKBIA, and ICAM1. Contrary to the wP individuals, this subset displayed increased PT-specific IgE responses after boost and higher antigen-specific IgG4 and IgG3 antibodies against FHA and FIM2/3 at baseline and after boost. Overall, the results show that, while broad immune response patterns to Tdap boost overlap between aP- and wP-primed individuals, a subset of aP-primed individuals present a divergent response. These findings provide candidate targets to study the causes and correlates of waning immunity after aP vaccination.

Authors

Ricardo da Silva Antunes, Ferran Soldevila, Mikhail Pomaznoy, Mariana Babor, Jason Bennett, Yuan Tian, Natalie Khalil, Yu Qian, Aishwarya Mandava, Richard H. Scheuermann, Mario Cortese, Bali Pulendran, Christopher D. Petro, Adrienne P. Gilkes, Lisa A. Purcell, Alessandro Sette, Bjoern Peters

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Abstract

Both innate and adaptive immune cells are critical players in autoimmune destruction of insulin-producing β cells in type 1 diabetes. However, the early pathogenic events triggering the recruitment and activation of innate immune cells in islets remain obscure. Here we show that circulating fatty acid binding protein 4 (FABP4) level was significantly elevated in patients with type 1 diabetes and their first-degree relatives and positively correlated with the titers of several islet autoantibodies. In nonobese diabetic (NOD) mice, increased FABP4 expression in islet macrophages started from the neonatal period, well before the occurrence of overt diabetes. Furthermore, the spontaneous development of autoimmune diabetes in NOD mice was markedly reduced by pharmacological inhibition or genetic ablation of FABP4 or adoptive transfer of FABP4-deficient bone marrow cells. Mechanistically, FABP4 activated innate immune responses in islets by enhancing the infiltration and polarization of macrophages to proinflammatory M1 subtype, thus creating an inflammatory milieu required for activation of diabetogenic CD8+ T cells and shift of CD4+ helper T cells toward Th1 subtypes. These findings demonstrate FABP4 as a possible early mediator for β cell autoimmunity by facilitating crosstalk between innate and adaptive immune cells, suggesting that pharmacological inhibition of FABP4 may represent a promising therapeutic strategy for autoimmune diabetes.

Authors

Yang Xiao, Lingling Shu, Xiaoping Wu, Yang Liu, Lai Yee Cheong, Boya Liao, Xiaoyu Xiao, Ruby L.C. Hoo, Zhiguang Zhou, Aimin Xu

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Abstract

There are approximately 44,000 cases of human papillomavirus–associated (HPV-associated) cancer each year in the United States, most commonly caused by HPV types 16 and 18. Prophylactic vaccines successfully prevent healthy people from acquiring HPV infections via HPV-specific antibodies. In order to treat established HPV-associated malignancies, however, new therapies are necessary. Multiple recombinant gorilla adenovirus HPV vaccine constructs were evaluated in NSG-β2m–/– peripheral blood mononuclear cell–humanized mice bearing SiHa, a human HPV16+ cervical tumor, and/or in the syngeneic HPV16+ TC-1 model. PRGN-2009 is a therapeutic gorilla adenovirus HPV vaccine containing multiple cytotoxic T cell epitopes of the viral oncoproteins HPV 16/18 E6 and E7, including T cell enhancer agonist epitopes. PRGN-2009 treatment reduced tumor volume and increased CD8+ and CD4+ T cells in the tumor microenvironment of humanized mice bearing the human cervical tumor SiHa. PRGN-2009 monotherapy in the syngeneic TC-1 model also reduced tumor volumes and weights, generated high levels of HPV16 E6–specific T cells, and increased multifunctional CD8+ and CD4+ T cells in the tumor microenvironment. These studies provide the first evaluation to our knowledge of a therapeutic gorilla adenovirus HPV vaccine, PRGN-2009, showing promising preclinical antitumor efficacy and induction of HPV-specific T cells, along with the rationale for its evaluation in clinical trials.

Authors

Samuel T. Pellom, Claire Smalley Rumfield, Y. Maurice Morillon II, Nicholas Roller, Lisa K. Poppe, Douglas E. Brough, Helen Sabzevari, Jeffrey Schlom, Caroline Jochems

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Abstract

Human pluripotent stem cells (PSCs), which are composed of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), provide an opportunity to advance cardiac cell therapy–based clinical trials. However, an important hurdle that must be overcome is the risk of teratoma formation after cell transplantation due to the proliferative capacity of residual undifferentiated PSCs in differentiation batches. To tackle this problem, we propose the use of a minimal noncardiotoxic doxorubicin dose as a purifying agent to selectively target rapidly proliferating stem cells for cell death, which will provide a purer population of terminally differentiated cardiomyocytes before cell transplantation. In this study, we determined an appropriate in vitro doxorubicin dose that (a) eliminates residual undifferentiated stem cells before cell injection to prevent teratoma formation after cell transplantation and (b) does not cause cardiotoxicity in ESC-derived cardiomyocytes (CMs) as demonstrated through contractility analysis, electrophysiology, topoisomerase activity assay, and quantification of reactive oxygen species generation. This study establishes a potentially novel method for tumorigenic-free cell therapy studies aimed at clinical applications of cardiac cell transplantation.

Authors

Tony Chour, Lei Tian, Edward Lau, Dilip Thomas, Ilanit Itzhaki, Olfat Malak, Joe Z. Zhang, Xulei Qin, Mirwais Wardak, Yonggang Liu, Mark Chandy, Katelyn E. Black, Maggie P.Y. Lam, Evgenios Neofytou, Joseph C. Wu

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Abstract

The Janus kinase/signal transducers and activators of transcription (JAK/STAT) are key intracellular mediators in the signal transduction of many cytokines and growth factors. Common γ chain cytokines and interferon-γ that use the JAK/STAT pathway to induce biological responses have been implicated in the pathogenesis of alopecia areata (AA), a T cell–mediated autoimmune disease of the hair follicle. We previously showed that therapeutic targeting of JAK/STAT pathways using the first-generation JAK1/2 inhibitor, ruxolitinib, and the pan-JAK inhibitor, tofacitinib, was highly effective in the treatment of human AA, as well as prevention and reversal of AA in the C3H/HeJ mouse model. To better define the role of individual JAKs in the pathogenesis of AA, in this study, we tested and compared the efficacy of several next-generation JAK-selective inhibitors in the C3H/HeJ mouse model of AA, using both systemic and topical delivery. We found that JAK1-selective inhibitors as well as JAK3-selective inhibitors robustly induced hair regrowth and decreased AA-associated inflammation, whereas several JAK2-selective inhibitors failed to restore hair growth in treated C3H/HeJ mice with AA. Unlike JAK1, which is broadly expressed in many tissues, JAK3 expression is largely restricted to hematopoietic cells. Our study demonstrates inhibiting JAK3 signaling is sufficient to prevent and reverse disease in the preclinical model of AA.

Authors

Zhenpeng Dai, James Chen, Yuqian Chang, Angela M. Christiano

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Abstract

With the advent of cancer immunology, mass cytometry has been increasingly employed to characterize the responses to cancer therapies and the tumor microenvironment (TME). One of its most notable applications is efficient multiplexing of samples into batches by dedicating a number of metal isotope channels to barcodes, enabling robust data acquisition and analysis. Barcoding is most effective when markers are present in all cells of interest. While CD45 has been shown to be a reliable marker for barcoding all immune cells in a given sample, a strategy to reliably barcode mouse cancer cells has not been demonstrated. To this end, we identified CD29 and CD98 as markers widely expressed by commonly used mouse cancer cell lines. We conjugated anti-CD29 and anti-CD98 antibodies to cadmium or indium metals and validated their utility in 10-plex barcoding of live cells. Finally, we established a potentially novel barcoding system incorporating the combination of CD29, CD98, and CD45 to multiplex 10 tumors from s.c. MC38 and KPC tumor models, while successfully recapitulating the known contrast in the PD1-PDL1 axis between the 2 models. The ability to barcode tumor cells along with immune cells empowers the interrogation of the tumor-immune interactions in mouse TME studies.

Authors

Soren Charmsaz, Nicole Gross, Elizabeth Jaffee, Won Jin Ho

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Abstract

Macrophage-mediated inflammatory response has been implicated in the pathogenesis of obesity and insulin resistance. Brd4 has emerged as a key regulator in the innate immune response. However, the role of Brd4 in obesity-associated inflammation and insulin resistance remains uncharacterized. Here, we demonstrated that myeloid lineage-specific Brd4 knockout (Brd4-CKO) mice were protected from high-fat diet–induced (HFD-induced) obesity with less fat accumulation, higher energy expenditure, and increased lipolysis in adipose tissue. Brd4-CKO mice fed a HFD also displayed reduced local and systemic inflammation with improved insulin sensitivity. RNA-Seq of adipose tissue macrophages (ATMs) from HFD-fed WT and Brd4-CKO mice revealed that expression of antilipolytic factor Gdf3 was significantly decreased in ATMs of Brd4-CKO mice. We also found that Brd4 bound to the promoter and enhancers of Gdf3 to facilitate PPARγ-dependent Gdf3 expression in macrophages. Furthermore, Brd4-mediated expression of Gdf3 acted as a paracrine signal targeting adipocytes to suppress the expression of lipases and the associated lipolysis in cultured cells and mice. Controlling the expression of Gdf3 in ATMs could be one of the mechanisms by which Brd4 modulates lipid metabolism and diet-induced obesity. This study suggests that Brd4 could be a potential therapeutic target for obesity and insulin resistance.

Authors

Xiangming Hu, Xingchen Dong, Guo Li, Yanheng Chen, Jinjing Chen, Xiaoxin He, Hao Sun, Dong-Hyun Kim, Jongsook Kim Kemper, Lin-Feng Chen

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Abstract

Here, we report on the identification of Itga7-expressing muscle-resident glial cells activated by loss of neuromuscular junction (NMJ) integrity. Gene expression analysis at the bulk and single-cell level revealed that these cells are distinct from Itga7-expressing muscle satellite cells. We show that a selective activation and expansion of Itga7+ glial cells occur in response to muscle nerve lesion. Upon activation, muscle glial–derived progenies expressed neurotrophic genes, including nerve growth factor receptor, which enables their isolation by FACS. We show that activated muscle glial cells also expressed genes potentially implicated in extracellular matrix remodeling at NMJs. We found that tenascin C, which was highly expressed by muscle glial cells, activated upon nerve injury and preferentially localized to NMJ. Interestingly, we observed that the activation of muscle glial cells by acute nerve injury was reversible upon NMJ repair. By contrast, in a mouse model of ALS, in which NMJ degeneration is progressive, muscle glial cells steadily increased over the course of the disease. However, they exhibited an impaired neurotrophic activity, suggesting that pathogenic activation of glial cells may be implicated in ALS progression.

Authors

Daisy Proietti, Lorenzo Giordani, Marco De Bardi, Chiara D’Ercole, Biliana Lozanoska-Ochser, Susanna Amadio, Cinzia Volonté, Sara Marinelli, Antoine Muchir, Marina Bouché, Giovanna Borsellino, Alessandra Sacco, Pier Lorenzo Puri, Luca Madaro

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Abstract

Secretory protein misfolding has been linked to ER stress and cell death. We expressed a TGrdw transgene encoding TG-G(2298)R, a misfolded mutant thyroglobulin reported to be linked to thyroid cell death. When the TGrdw transgene was expressed at low level in thyrocytes of TGcog/cog mice that experienced severe ER stress, we observed increased thyrocyte cell death and increased expression of CIDE-A (cell death-inducing DFFA-like effector-A, a protein of lipid droplets) in whole thyroid gland. Here we demonstrate that acute ER stress in cultured PCCL3 thyrocytes increases Cidea mRNA levels, maintained at least in part by increased mRNA stability, while being negatively regulated by activating transcription factor 6 — with similar observations that ER stress increases Cidea mRNA levels in other cell types. CIDE-A protein is sensitive to proteasomal degradation yet is stabilized by ER stress, and elevated expression levels accompany increased cell death. Unlike acute ER stress, PCCL3 cells adapted and surviving chronic ER stress maintained a disproportionately lower relative mRNA level of Cidea compared with that of other, classical ER stress markers, as well as a blunted Cidea mRNA response to a new, unrelated acute ER stress challenge. We suggest that CIDE-A is a novel marker linked to a noncanonical ER stress response program, with implications for cell death and survival.

Authors

Yoshiaki Morishita, Aaron P. Kellogg, Dennis Larkin, Wei Chen, Suryakiran Vadrevu, Leslie Satin, Ming Liu, Peter Arvan

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Abstract

Autoimmune diseases are characterized by a breakdown of immune tolerance partly due to environmental factors. The short-chain fatty acid acetate, derived mostly from gut microbial fermentation of dietary fiber, promotes antiinflammatory Tregs and protects mice from type 1 diabetes, colitis, and allergies. Here, we show that the effects of acetate extend to another important immune subset involved in tolerance, the IL-10–producing regulatory B cells (B10 cells). Acetate directly promoted B10 cell differentiation from mouse B1a cells both in vivo and in vitro. These effects were linked to metabolic changes through the increased production of acetyl-coenzyme A, which fueled the TCA cycle and promoted posttranslational lysine acetylation. Acetate also promoted B10 cells from human blood cells through similar mechanisms. Finally, we identified that dietary fiber supplementation in healthy individuals was associated with increased blood-derived B10 cells. Direct delivery of acetate or indirect delivery via diets or bacteria that produce acetate might be a promising approach to restore B10 cells in noncommunicable diseases.

Authors

C.I. Daïen, J. Tan, R. Audo, J. Mielle, L.E. Quek, J.R. Krycer, A. Angelatos, M. Duraes, G. Pinget, D. Ni, R. Robert, M.J. Alam, M.C.B. Amian, F. Sierro, A. Parmar, G. Perkins, S. Hoque, A.K. Gosby, S.J. Simpson, R.V. Ribeiro, C.R. Mackay, L. Macia

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Abstract

The drive to withstand environmental stresses and defend against invasion is a universal trait extant in all forms of life. While numerous canonical signaling cascades have been characterized in detail, it remains unclear how these pathways interface to generate coordinated responses to diverse stimuli. To dissect these connections, we followed heparanase (HPSE), a protein best known for its endoglycosidic activity at the extracellular matrix but recently recognized to drive various forms of late-stage disease through unknown mechanisms. Using herpes simplex virus-1 (HSV-1) infection as a model cellular perturbation, we demonstrate that HPSE acts beyond its established enzymatic role to restrict multiple forms of cell-intrinsic defense and facilitate host cell reprogramming by the invading pathogen. We reveal that cells devoid of HPSE are innately resistant to infection and counteract viral takeover through multiple amplified defense mechanisms. With a unique grasp of the fundamental processes of transcriptional regulation and cell death, HPSE represents a potent cellular intersection with broad therapeutic potential.

Authors

Alex Agelidis, Benjamin A. Turturice, Rahul K. Suryawanshi, Tejabhiram Yadavalli, Dinesh Jaishankar, Joshua Ames, James Hopkins, Lulia Koujah, Chandrashekhar D. Patil, Satvik R. Hadigal, Evan J. Kyzar, Anaamika Campeau, Jacob M. Wozniak, David J. Gonzalez, Israel Vlodavsky, Jin-ping Li, David L. Perkins, Patricia W. Finn, Deepak Shukla

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Abstract

To unequivocally address their unresolved intimate structures in blood, we scrutinized the size distribution of circulating cell-free DNA (cfDNA) using whole-genome sequencing (WGS) from both double- and single-strand DNA library preparations (DSP and SSP, n = 7) and using quantitative PCR (Q-PCR, n = 116). The size profile in healthy individuals was remarkably homogenous when using DSP sequencing or SSP sequencing. CfDNA size profile had a characteristic nucleosome fragmentation pattern. Overall, our data indicate that the proportion of cfDNA inserted in mono-nucleosomes, di-nucleosomes, and chromatin of higher molecular size (>1000 bp) can be estimated as 67.5% to 80%, 9.4% to 11.5%, and 8.5% to 21.0%, respectively. Although DNA on single chromatosomes or mono-nucleosomes is detectable, our data revealed that cfDNA is highly nicked (97%–98%) on those structures, which appear to be subjected to continuous nuclease activity in the bloodstream. Fragments analysis allows the distinction of cfDNA of different origins: first, cfDNA size profile analysis may be useful in cfDNA extract quality control; second, subtle but reliable differences between metastatic colorectal cancer patients and healthy individuals vary with the proportion of malignant cell-derived cfDNA in plasma extracts, pointing to a higher degree of cfDNA fragmentation and nuclease activity in samples with high malignant cell cfDNA content.

Authors

Cynthia Sanchez, Benoit Roch, Thibault Mazard, Philippe Blache, Zahra Al Amir Dache, Brice Pastor, Ekaterina Pisareva, Rita Tanos, Alain R. Thierry

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Abstract

Vaccine delivery technologies are mainly designed to minimally invasively deliver vaccines to target tissues with little or no adjuvant effects. This study presents a prototype laser-based powder delivery (LPD) with inherent adjuvant effects for more immunogenic vaccination without incorporation of external adjuvants. LPD takes advantage of aesthetic ablative fractional laser to generate skin microchannels to support high-efficient vaccine delivery and at the same time creates photothermal stress in microchannel-surrounding tissues to boost vaccination. LPD could significantly enhance pandemic influenza 2009 H1N1 vaccine immunogenicity and protective efficacy as compared with needle-based intradermal delivery in murine models. The ablative fractional laser was found to induce host DNA release, activate NLR family pyrin domain containing 3 inflammasome, and stimulate IL-1β release despite their dispensability for laser adjuvant effects. Instead, the ablative fractional laser activated MyD88 to mediate its adjuvant effects by potentiation of antigen uptake, maturation, and migration of dendritic cells. LPD also induced minimal local or systemic adverse reactions due to the microfractional and sustained vaccine delivery. Our data support the development of self-adjuvanted vaccine delivery technologies by intentional induction of well-controlled tissue stress to alert innate immune systems for more immunogenic vaccination.

Authors

Zhuofan Li, Yan Cao, Yibo Li, Yiwen Zhao, Xinyuan Chen

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Abstract

Morphologic examination of tissue biopsies is essential for histopathological diagnosis. However, accurate and scalable cellular quantification in human samples remains challenging. Here, we present a deep learning–based approach for antigen-specific cellular morphometrics in human kidney biopsies, which combines indirect immunofluorescence imaging with U-Net–based architectures for image-to-image translation and dual segmentation tasks, achieving human-level accuracy. In the kidney, podocyte loss represents a hallmark of glomerular injury and can be estimated in diagnostic biopsies. Thus, we profiled over 27,000 podocytes from 110 human samples, including patients with antineutrophil cytoplasmic antibody–associated glomerulonephritis (ANCA-GN), an immune-mediated disease with aggressive glomerular damage and irreversible loss of kidney function. We identified previously unknown morphometric signatures of podocyte depletion in patients with ANCA-GN, which allowed patient classification and, in combination with routine clinical tools, showed potential for risk stratification. Our approach enables robust and scalable molecular morphometric analysis of human tissues, yielding deeper biological insights into the human kidney pathophysiology.

Authors

Marina Zimmermann, Martin Klaus, Milagros N. Wong, Ann-Katrin Thebille, Lukas Gernhold, Christoph Kuppe, Maurice Halder, Jennifer Kranz, Nicola Wanner, Fabian Braun, Sonia Wulf, Thorsten Wiech, Ulf Panzer, Christian F. Krebs, Elion Hoxha, Rafael Kramann, Tobias B. Huber, Stefan Bonn, Victor G. Puelles

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Abstract

To identify small molecules that shield mammalian sensory hair cells from the ototoxic side effects of aminoglycoside antibiotics, 10,240 compounds were initially screened in zebrafish larvae, selecting for those that protected lateral-line hair cells against neomycin and gentamicin. When the 64 hits from this screen were retested in mouse cochlear cultures, 8 protected outer hair cells (OHCs) from gentamicin in vitro without causing hair-bundle damage. These 8 hits shared structural features and blocked, to varying degrees, the OHC’s mechano-electrical transducer (MET) channel, a route of aminoglycoside entry into hair cells. Further characterization of one of the strongest MET channel blockers, UoS-7692, revealed it additionally protected against kanamycin and tobramycin and did not abrogate the bactericidal activity of gentamicin. UoS-7692 behaved, like the aminoglycosides, as a permeant blocker of the MET channel; significantly reduced gentamicin–Texas red loading into OHCs; and preserved lateral-line function in neomycin-treated zebrafish. Transtympanic injection of UoS-7692 protected mouse OHCs from furosemide/kanamycin exposure in vivo and partially preserved hearing. The results confirmed the hair-cell MET channel as a viable target for the identification of compounds that protect the cochlea from aminoglycosides and provide a series of hit compounds that will inform the design of future otoprotectants.

Authors

Emma J. Kenyon, Nerissa K. Kirkwood, Siân R. Kitcher, Richard J. Goodyear, Marco Derudas, Daire M. Cantillon, Sarah Baxendale, Antonio de la Vega de León, Virginia N. Mahieu, Richard T. Osgood, Charlotte Donald Wilson, James C. Bull, Simon J. Waddell, Tanya T. Whitfield, Simon E. Ward, Corné J. Kros, Guy P. Richardson

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Abstract

Chronic inflammation and immune dysfunction play a key role in the development of non-AIDS–related comorbidities. The aim of our study was to characterize the functional phenotype of immune cells in people living with HIV (PLHIV). We enrolled a cross-sectional cohort study of PLHIV on stable antiretroviral therapy and healthy controls. We assessed ex vivo cytokine production capacity and transcriptomics of monocytes and T cells upon bacterial, fungal, and viral stimulation. PLHIV exhibited an exacerbated proinflammatory profile in monocyte-derived cytokines, but not in lymphocyte-derived cytokines. Particularly, the production of the IL-1β to imiquimod, E. coli LPS, and Mycobacterium tuberculosis was increased, and this production correlated with plasma concentrations of high-sensitivity C-reactive protein and soluble CD14. This increase in monocyte responsiveness remained stable over time in subsequent blood sampling after more than 1 year. Transcriptome analyses confirmed priming of the monocyte IL-1β pathway, consistent with a monocyte-trained immunity phenotype. Increased plasma concentrations of β-glucan, a well-known inducer of trained immunity, were associated with increased innate cytokine responses. Monocytes of PLHIV exhibited a sustained proinflammatory immune phenotype with priming of the IL-1β pathway. Training of the innate immune system in PLHIV likely plays a role in long-term HIV complications and provides a promising therapeutic target for inflammation-related comorbidities.

Authors

Wouter A. van der Heijden, Lisa Van de Wijer, Farid Keramati, Wim Trypsteen, Sofie Rutsaert, Rob ter Horst, Martin Jaeger, Hans J.P.M. Koenen, Hendrik G. Stunnenberg, Irma Joosten, Paul E. Verweij, Jan van Lunzen, Charles A. Dinarello, Leo A.B. Joosten, Linos Vandekerckhove, Mihai G. Netea, André J.A.M. van der Ven, Quirijn de Mast

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Abstract

Gene replacement for Duchenne muscular dystrophy (DMD) with micro-dystrophins has entered clinical trials, but efficacy in preventing heart failure is unknown. Although most patients with DMD die from heart failure, cardiomyopathy is undetectable until the teens, so efficacy from trials in young boys will be unknown for a decade. Available DMD animal models were sufficient to demonstrate micro-dystrophin efficacy on earlier onset skeletal muscle pathology underlying loss of ambulation and respiratory insufficiency in patients. However, no mouse models progressed into heart failure, and dog models showed highly variable progression insufficient to evaluate efficacy of micro-dystrophin or other therapies on DMD heart failure. To overcome this barrier, we have generated the first DMD mouse model to our knowledge that reproducibly progresses into heart failure. This model shows cardiac inflammation and fibrosis occur prior to reduced function. Fibrosis does not continue to accumulate, but inflammation persists after function declines. We used this model to test micro-dystrophin gene therapy efficacy on heart failure prevention for the first time. Micro-dystrophin prevented declines in cardiac function and prohibited onset of inflammation and fibrosis. This model will allow identification of committed pathogenic steps to heart failure and testing of genetic and nongenetic therapies to optimize cardiac care for patients with DMD.

Authors

Zachary M. Howard, Lisa E. Dorn, Jeovanna Lowe, Megan D. Gertzen, Pierce Ciccone, Neha Rastogi, Guy L. Odom, Federica Accornero, Jeffrey S. Chamberlain, Jill A. Rafael-Fortney

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Abstract

Studies of human hepatitis B virus (HBV) immune pathogenesis are hampered by limited access to liver tissues and technologies for detailed analyses. Here, utilizing imaging mass cytometry (IMC) to simultaneously detect 30 immune, viral, and structural markers in liver biopsies from patients with hepatitis B e antigen+ (HBeAg+) chronic hepatitis B, we provide potentially novel comprehensive visualization, quantitation, and phenotypic characterizations of hepatic adaptive and innate immune subsets that correlated with hepatocellular injury, histological fibrosis, and age. We further show marked correlations between adaptive and innate immune cell frequencies and phenotype, highlighting complex immune interactions within the hepatic microenvironment with relevance to HBV pathogenesis.

Authors

Daniel Traum, Yue J. Wang, Kathleen B. Schwarz, Jonathan Schug, David K.H. Wong, Harry L.A. Janssen, Norah A. Terrault, Mandana Khalili, Abdus S. Wahed, Karen F. Murray, Phillip Rosenthal, Simon C. Ling, Norberto Rodriguez-Baez, Richard K. Sterling, Daryl T.Y. Lau, Timothy M. Block, Michael D. Feldman, Elizabeth E. Furth, William M. Lee, David E. Kleiner, Anna S. Lok, Klaus H. Kaestner, Kyong-Mi Chang

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Abstract

Liver regeneration is critical to survival after traumatic injuries, exposure to hepatotoxins, or surgical interventions, yet the underlying signaling and metabolic pathways remain unclear. In this study, we show that hepatocyte-specific loss of the mitochondrial deacetylase SIRT3 drastically impairs regeneration and worsens mitochondrial function after partial hepatectomy. Sirtuins, including SIRT3, require NAD as a cosubstrate. We previously showed that the NAD precursor nicotinamide riboside (NR) promotes liver regeneration, but whether this involves sirtuins has not been tested. Here, we show that despite their NAD dependence and critical roles in regeneration, neither SIRT3 nor its nuclear counterpart SIRT1 is required for NR to enhance liver regeneration. NR improves mitochondrial respiration in regenerating WT or mutant livers and rapidly increases oxygen consumption and glucose output in cultured hepatocytes. Our data support a direct enhancement of mitochondrial redox metabolism as the mechanism mediating improved liver regeneration after NAD supplementation and exclude signaling via SIRT1 and SIRT3. Therefore, we provide the first evidence to our knowledge for an essential role for a mitochondrial sirtuin during liver regeneration and insight into the beneficial effects of NR.

Authors

Sarmistha Mukherjee, James Mo, Lauren M. Paolella, Caroline E. Perry, Jade Toth, Mindy M. Hugo, Qingwei Chu, Qian Tong, Karthikeyani Chellappa, Joseph A. Baur

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Abstract

INTRODUCTION The clinical course of coronavirus 2019 (COVID-19) is heterogeneous, ranging from mild to severe multiorgan failure and death. In this study, we analyzed cell-free DNA (cfDNA) as a biomarker of injury to define the sources of tissue injury that contribute to such different trajectories.METHODS We conducted a multicenter prospective cohort study to enroll patients with COVID-19 and collect plasma samples. Plasma cfDNA was subject to bisulfite sequencing. A library of tissue-specific DNA methylation signatures was used to analyze sequence reads to quantitate cfDNA from different tissue types. We then determined the correlation of tissue-specific cfDNA measures to COVID-19 outcomes. Similar analyses were performed for healthy controls and a comparator group of patients with respiratory syncytial virus and influenza.RESULTS We found markedly elevated levels and divergent tissue sources of cfDNA in COVID-19 patients compared with patients who had influenza and/or respiratory syncytial virus and with healthy controls. The major sources of cfDNA in COVID-19 were hematopoietic cells, vascular endothelium, hepatocytes, adipocytes, kidney, heart, and lung. cfDNA levels positively correlated with COVID-19 disease severity, C-reactive protein, and D-dimer. cfDNA profile at admission identified patients who subsequently required intensive care or died during hospitalization. Furthermore, the increased cfDNA in COVID-19 patients generated excessive mitochondrial ROS (mtROS) in renal tubular cells in a concentration-dependent manner. This mtROS production was inhibited by a TLR9-specific antagonist.CONCLUSION cfDNA maps tissue injury that predicts COVID-19 outcomes and may mechanistically propagate COVID-19–induced tissue injury.FUNDING Intramural Targeted Anti–COVID-19 grant, NIH.

Authors

Temesgen E. Andargie, Naoko Tsuji, Fayaz Seifuddin, Moon Kyoo Jang, Peter S.T. Yuen, Hyesik Kong, Ilker Tunc, Komudi Singh, Ananth Charya, Kenneth Wilkins, Steven Nathan, Andrea Cox, Mehdi Pirooznia, Robert A. Star, Sean Agbor-Enoh

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Review
Abstract

Oxygen-sensing mechanisms allow cells to adapt and respond to changes in cellular oxygen tension, including hypoxic conditions. Hypoxia-inducible factor (HIF) is a central mediator in this fundamental adaptive response, and has critical functions in normal and disease physiology. Viruses have been shown to manipulate HIFs during their life cycle to facilitate replication and invasion. Conversely, HIFs are also implicated in the development of the host immune system and response to viral infections. Here, we highlight the recent revelations of host-pathogen interactions that involve the hypoxic response pathway and the role of HIF in emerging viral infectious diseases, as well as discussing potential antiviral therapeutic strategies targeting the HIF signaling axis.

Authors

Richard Huang, Melissa Huestis, Esther Shuyi Gan, Eng Eong Ooi, Michael Ohh

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Corrigendums
Abstract

Authors

Archana S. Nagaraja, Robert L. Dood, Guillermo Armaiz-Pena, Yu Kang, Sherry Y. Wu, Julie K. Allen, Nicholas B. Jennings, Lingegowda S. Mangala, Sunila Pradeep, Yasmin Lyons, Monika Haemmerle, Kshipra M. Gharpure, Nouara C. Sadaoui, Cristian Rodriguez-Aguayo, Cristina Ivan, Ying Wang, Keith Baggerly, Prahlad Ram, Gabriel Lopez-Berestein, Jinsong Liu, Samuel C. Mok, Lorenzo Cohen, Susan K. Lutgendorf, Steve W. Cole, Anil K. Sood

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Abstract

Authors

Lingegowda S. Mangala, Hongyu Wang, Dahai Jiang, Sherry Y. Wu, Anoma Somasunderam, David E. Volk, Ganesh L. R. Lokesh, Xin Li, Sunila Pradeep, Xianbin Yang, Monika Haemmerle, Cristian Rodriguez-Aguayo, Archana S Nagaraja, Rajesha Rupaimoole, Emine Bayraktar, Recep Bayraktar, Li Li, Takemi Tanaka, Wei Hu, Cristina Ivan, Kshipra M Gharpure, Michael H. McGuire, Varatharasa Thiviyanathan, Xinna Zhang, Sourindra N. Maiti, Nataliya Bulayeva, Hyun-Jin Choi, Piotr L. Dorniak, Laurence J.N. Cooper, Kevin P. Rosenblatt, Gabriel Lopez-Berestein, David G. Gorenstein, Anil K. Sood

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Abstract

Extensive activation of glial cells during a latent period has been well documented in various animal models of epilepsy. However, it remains unclear whether activated glial cells contribute to epileptogenesis; i.e., the chronically persistent process leading to epilepsy. Particularly, it is not clear whether inter-glial communication between different types of glial cells contributes to epileptogenesis, as past literature mainly focused on one type of glial cell. Here, we show that temporally distinct activation profiles of microglia and astrocytes collaboratively contribute to epileptogenesis in a drug-induced status epilepticus model. We found that reactive microglia appeared first, followed by reactive astrocytes and increased susceptibility to seizures. Reactive astrocytes exhibited larger Ca2+ signals mediated by IP3R2, whereas deletion of this type of Ca2+ signaling reduced seizure susceptibility after status epilepticus. Immediate, but not late, pharmacological inhibition of microglial activation prevented subsequent reactive astrocytes, aberrant astrocyte Ca2+ signaling, and the enhanced seizure susceptibility. These findings indicate that the sequential activation of glial cells constitutes a cause of epileptogenesis after status epilepticus. Thus, our findings suggest that the therapeutic target to prevent epilepsy after status epilepticus should be shifted from microglia (early phase) to astrocytes (late phase).

Authors

Fumikazu Sano, Eiji Shigetomi, Youichi Shinozaki, Haruka Tsuzukiyama, Kozo Saito, Katsuhiko Mikoshiba, Hiroshi Horiuchi, Dennis Lawrence Cheung, Junichi Nabekura, Kanji Sugita, Masao Aihara, Schuichi Koizumi

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Abstract

Idiopathic pulmonary fibrosis is a progressive fibrotic lung disease. We previously identified fibrogenic mesenchymal progenitor cells (MPCs) in the lungs of IPF patients that serve as an obligatory driver of progressive fibrosis. Recent single cell RNA sequencing work revealed that IPF MPCs with the highest transcriptomic network entropy differ the most from control MPCs; and that CD44 was a marker of these IPF MPCs. We hypothesize that IPF MPCs with high CD44 (CD44hi) expression will display enhanced fibrogenicity. We demonstrate that CD44 expressing MPCs are present at the periphery of the IPF fibroblastic focus, placing them in regions of active fibrogenesis. In a humanized mouse xenograft model, CD44hi IPF MPCs are more fibrogenic than CD44lo IPF MPCs and knock-down of CD44 diminishes their fibrogenicity. CD44hi IPF MPCs display increased expression of pluripotency markers and self-renewal compared to CD44lo IPF MPCs; properties potentiated by IL-8. The mechanism involves the accumulation of CD44 within the nucleus where it associates with the chromatin modulator protein BRG1 and the Zeb1 transcription factor. This CD44/BRG1/Zeb1 nuclear protein complex targets the Sox2 gene promoting its upregulation and self-renewal. Our data implicates CD44 interaction with the epigenetic modulator protein Brg1 in conveying IPF MPCs with cell-autonomous fibrogenicity.

Authors

Libang Yang, Hong Xia, Karen A. Smith, Adam Gilbertsen, Daniel Beisang, Jonathan Kuo, Peter B. Bitterman, Craig A. Henke

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Abstract

T cell receptor (TCR) triggering by antigen results in metabolic reprogramming that, in turn, facilitates T cells’ exit from quiescence. The increased nutrient requirements of activated lymphocytes are met in part by upregulation of cell surface transporters and enhanced uptake of amino acids, fatty acids and glucose from the environment. However, the role of intracellular pathways of amino acid biosynthesis in T cell activation is relatively unexplored. Asparagine (Asn) is a non-essential amino acid that can be synthesized intracellularly through the glutamine-hydrolyzing enzyme asparagine synthetase (ASNS). We set out to define the requirements for uptake of extracellular Asn and ASNS activity in CD8+ T cell activation. At early timepoints of activation in vitro, CD8+ T cells expressed little or no ASNS and, as a consequence, viability and TCR-stimulated growth, activation and metabolic reprogramming were substantially impaired under conditions of Asn deprivation. At later timepoints (>24h of activation), TCR-induced mTOR-dependent signals resulted in upregulation of ASNS, that endowed CD8+ T cells with the capacity to function independently of extracellular Asn. Thus, our data suggest that the coordinated upregulation of ASNS expression and uptake of extracellular Asn is involved in optimal T cell effector responses.

Authors

Helen Carrasco Hope, Rebecca J. Brownlie, Christopher M. Fife, Lynette Steele, Mihaela Lorger, Robert J. Salmond

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Abstract

Telomerase catalyzes chromosome end replication in stem cells and other long-lived cells. Mutations in telomerase or telomere-related genes result in diseases known as telomeropathies. Telomerase is recruited to chromosome ends by the ACD/TPP1 protein (TPP1 hereafter), a component of the shelterin complex that protects chromosome ends from unwanted end-joining. TPP1 facilitates end-protection by binding shelterin proteins POT1 and TIN2. TPP1 variants have been associated with telomeropathies, but remain poorly characterized in vivo. Disease variants and mutagenesis scans provide efficient avenues to interrogate the distinct physiological roles of TPP1. Here, we conduct mutagenesis in the TIN2- and POT1-binding domains of TPP1 to discover mutations that dissect TPP1’s functions. Our results extend upon current structural data to reveal that the TPP1-TIN2 interface is more extensive than previously thought, and highlight the robustness of the POT1-TPP1 interface. Introduction of separation-of-function mutants alongside known TPP1 telomeropathy mutations in mouse hematopoietic stem cells (mHSCs) lacking endogenous TPP1 demonstrated a clear phenotypic demarcation. TIN2- and POT1-binding mutants were unable to rescue mHSC failure resulting from end-deprotection. In contrast, TPP1 telomeropathy mutations sustained mHSC viability, consistent with them selectively impacting end-replication. These results highlight the power of scanning mutagenesis in revealing structural interfaces and dissecting multifunctional genes.

Authors

Sherilyn Grill, Shilpa Padmanaban, Ann Friedman, Eric Perkey, Frederick Allen, Valerie M. Tesmer, Jennifer Chase, Rami Khoriaty, Catherine E. Keegan, Ivan Maillard, Jayakrishnan Nandakumar

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Abstract

BACKGROUND. Methodology for estimation of cerebrospinal fluid (CSF) tracer clearance could have wide clinical application in predicting excretion of intrathecal drugs and metabolic solutes from brain metabolism, and for diagnostic work-up of cerebrospinal fluid disturbances. METHODS. The magnetic resonance imaging (MRI) contrast agent gadobutrol (Gadovist) was utilized as CSF tracer and injected into the lumbar CSF. Gadobutrol is contained outside blood vessels of the central nervous system (CNS) and is thus eliminated along extra-vascular pathways, analogous to many CNS metabolites and intrathecal drugs. Tracer enrichment was verified and assessed in CSF by MRI at level of the cisterna magna in parallel with obtaining blood samples through 48 hours. RESULTS. In a reference patient cohort (REF; n=29), both enrichment within CSF and blood coincided in time. Blood concentration profiles of gadobutrol through 48 hours varied between patients diagnosed with CSF leakage (n=4), idiopathic normal pressure hydrocephalus dementia (iNPH; n=7), pineal cysts (n=8), and idiopathic intracranial hypertension (IIH; n=4). CONCLUSION. Assessment of CSF tracer clearance is clinically feasible and may provide a way to predict extra-vascular clearance of intrathecal drugs and endogenous metabolites from the CNS. The peak concentration in blood (at about 10 hrs) preceded by far peak tracer enhancement at MRI in extra-cranial lymphatic structures (at about 24 hrs) as shown in previous studies, indicating a major role of the spinal canal in CSF clearance capacity. FUNDING. The work was supported by Department of Neurosurgery, Oslo university hospital, and Norwegian Institute for Air Research, Kjeller, Norway, and University of Oslo.

Authors

Per K. Eide, Espen Mariussen, Hilde Uggerud, Are H. Pripp, Aslan Lashkarivand, Bjørnar Hassel, Hege Christensen, Markus Herberg Hovd, Geir Ringstad

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