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Abstract

The lung is a specialized barrier organ that must tightly regulate interstitial fluid clearance and prevent infection in order to maintain effective gas exchange. Lymphatic vessels are important for these functions in other organs, but their roles in the lung have not been fully defined. In the present study, we evaluated how the lymphatic vasculature participates in lung homeostasis. Studies using mice carrying a lymphatic reporter allele revealed that, in contrast to other organs, lung lymphatic collecting vessels lack smooth muscle cells entirely, suggesting that forward lymph flow is highly dependent on movement and changes in pressure associated with respiration. Functional studies using C-type lectin domain family 2–deficient (CLEC2-deficient) mice in which lymph flow is impaired because of loss of lympho-venous hemostasis, or using inducible lung-specific ablation of lymphatic endothelial cells in a lung transplant model revealed that loss of lymphatic function leads to an inflammatory state characterized by the formation of tertiary lymphoid organs (TLOs). In addition, impaired lymphatic flow in mice resulted in hypoxia and features of lung injury that resembled emphysema. These findings reveal both a lung-specific mechanism of lymphatic physiology and a lung-specific consequence of lymphatic dysfunction that may contribute to chronic lung diseases that arise in association with TLO formation.

Authors

Hasina Outtz Reed, Liqing Wang, Jarrod Sonett, Mei Chen, Jisheng Yang, Larry Li, Petra Aradi, Zoltan Jakus, Jeanine D’Armiento, Wayne W. Hancock, Mark L. Kahn

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Abstract

Cortical bones account for more than 80% of human bone mass. The periosteum, a thin tissue that covers almost the entire bone surface, is essential for bone formation and regeneration. However, its osteogenic and bone regenerative abilities are not well studied. In this study, we found that macrophage-lineage cells recruit periosteum-derived cells (PDCs) for cortical bone formation. Knockout of colony-stimulating factor-1 eliminated macrophage-lineage cells and resulted in loss of PDCs with impaired periosteal bone formation. Moreover, macrophage-lineage tartrate-resistant acid phosphatase–positive (TRAP+) cells induced transcriptional expression of periostin and recruitment of PDCs to the periosteal surface through secretion of PDGF-BB, where the recruited PDCs underwent osteoblast differentiation coupled with type H vessel formation. We also found that subsets of Nestin+ and LepR+CD45–Ter119–CD31– cells (LepR+ PDCs) possess multipotent and self-renewal abilities and contribute to cortical bone formation. Nestin+ PDCs are found primarily during bone development, whereas LepR+ PDCs are essential for bone homeostasis in adult mice. Importantly, conditional knockout of Pdgfr-β in LepR+ cells impaired periosteal bone formation and regeneration. These findings uncover the essential role of periosteal macrophage-lineage cells in regulating periosteum homeostasis and regeneration.

Authors

Bo Gao, Ruoxian Deng, Yu Chai, Hao Chen, Bo Hu, Xiao Wang, Shouan Zhu, Yong Cao, Shuangfei Ni, Mei Wan, Liu Yang, Zhuojing Luo, Xu Cao

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Abstract

Preclinical studies demonstrate that rapid-acting antidepressants, including ketamine, require stimulation of mTORC1 signaling. This pathway is regulated by neuronal activity and endocrine and metabolic signals, notably including the amino acid leucine, which activates mTORC1 signaling via binding to the upstream regulator sestrin. Here, we examined the antidepressant actions of NV-5138, a highly selective small molecule modulator of sestrin that penetrates the blood-brain barrier. The results demonstrate that a single dose of NV-5138 produced rapid and long-lasting antidepressant effects and rapidly reversed anhedonia caused by chronic stress exposure. The antidepressant actions of NV-5138 required brain-derived neurotrophic factor (BDNF) release, as the behavioral responses were blocked by infusion of a BDNF-neutralizing Ab into the medial prefrontal cortex (mPFC) or, in mice, with a knockin of a BDNF polymorphism that blocked activity-dependent BDNF release. NV-5138 administration also rapidly increased synapse number and function in the mPFC and reversed the synaptic deficits caused by chronic stress. Together, the results demonstrate that NV-5138 produces rapid synaptic and antidepressant behavioral responses via activation of the mTORC1 pathway and BDNF signaling, indicating that pharmacological modulation of sestrin may be an attractive approach for the development of rapid-acting antidepressants.

Authors

Taro Kato, Santosh Pothula, Rong-Jian Liu, Catharine H. Duman, Rosemarie Terwilliger, George P. Vlasuk, Eddine Saiah, Seung Hahm, Ronald S. Duman

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Abstract

Increased urinary oxalate excretion (hyperoxaluria) promotes the formation of calcium oxalate crystals. Monogenic diseases due to hepatic enzyme deficiency result in chronic hyperoxaluria, promoting end-stage renal disease in children and young adults. Ethylene glycol poisoning also results in hyperoxaluria, promoting acute renal failure and frequently death. Stiripentol is an antiepileptic drug used to treat children affected by Dravet syndrome. It has been shown to inhibit neuronal lactate dehydrogenase 5 enzyme. As this isoenzyme is also the last step of hepatic oxalate production, we hypothesized that stiripentol would potentially reduce hepatic oxalate production and urine oxalate excretion. In vitro, stiripentol decreased the synthesis of oxalate by hepatocytes in a dose-dependent manner. In vivo, oral administration of stiripentol significantly reduced urine oxalate excretion in rats. Stiripentol protected the kidneys against calcium oxalate crystal deposits in acute ethylene glycol intoxication and chronic calcium oxalate nephropathy models. In both models, stiripentol significantly improved renal function. Patients affected by Dravet syndrome and treated with stiripentol had a lower urine oxalate excretion than control patients. A young girl affected by severe type I hyperoxaluria received stiripentol for several weeks, and urine oxalate excretion decreased by two-thirds. Stiripentol is a promising potential therapy against genetic hyperoxaluria and ethylene glycol poisoning.

Authors

Marine Le Dudal, Léa Huguet, Joëlle Perez, Sophie Vandermeersch, Elise Bouderlique, Ellie Tang, Carole Martori, Nicole Chemaly, Rima Nabbout, Jean-Philippe Haymann, Vincent Frochot, Laurent Baud, Georges Deschênes, Michel Daudon, Emmanuel Letavernier

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Abstract

The nuclear protein DEK is an endogenous DNA-binding chromatin factor regulating hematopoiesis. DEK is one of only 2 known secreted nuclear chromatin factors, but whether and how extracellular DEK regulates hematopoiesis is not known. We demonstrated that extracellular DEK greatly enhanced ex vivo expansion of cytokine-stimulated human and mouse hematopoietic stem cells (HSCs) and regulated HSC and hematopoietic progenitor cell (HPC) numbers in vivo and in vitro as determined both phenotypically (by flow cytometry) and functionally (through transplantation and colony formation assays). Recombinant DEK increased long-term HSC numbers and decreased HPC numbers through a mechanism mediated by the CXC chemokine receptor CXCR2 and heparan sulfate proteoglycans (HSPGs) (as determined utilizing Cxcr2–/– mice, blocking CXCR2 antibodies, and 3 different HSPG inhibitors) that was associated with enhanced phosphorylation of ERK1/2, AKT, and p38 MAPK. To determine whether extracellular DEK required nuclear function to regulate hematopoiesis, we utilized 2 mutant forms of DEK: one that lacked its nuclear translocation signal and one that lacked DNA-binding ability. Both altered HSC and HPC numbers in vivo or in vitro, suggesting the nuclear function of DEK is not required. Thus, DEK acts as a hematopoietic cytokine, with the potential for clinical applicability.

Authors

Maegan L. Capitano, Nirit Mor-Vaknin, Anjan K. Saha, Scott Cooper, Maureen Legendre, Haihong Guo, Rafael Contreras-Galindo, Ferdinand Kappes, Maureen A. Sartor, Christopher T. Lee, Xinxin Huang, David M. Markovitz, Hal E. Broxmeyer

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Abstract

In this issue of the JCI, Capitano et al. demonstrate that the secreted form of the DNA-binding chromatin factor DEK regulates hematopoiesis. It is known that DEK can be secreted by macrophages and other cells, but no function has been attached to secreted DEK. Capitano et al. showed that extracellular DEK activates signaling through the CXCL2 receptor, which in turn enhances the proliferation of hematopoietic stem cells and decreases hematopoietic progenitor cell numbers both in vivo and in vitro. These results offer the opportunity to expand transplantable stem cells to improve outcomes in patients undergoing bone marrow transplant.

Authors

David M. Bodine

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Abstract

Growing evidence implicates altered mTORC1 signaling cascades in the pathophysiology of depression, suggesting that direct modulation of mTORC1 signaling may offer novel therapeutic potential. In this issue of the JCI, Kato and colleagues reported that administration of NV-5138, a recently developed synthetic leucine analog, has a rapid and sustained antidepressant action in rat models via activation of mTORC1 signaling. The investigators also found that the antidepressant effect of NV-5138 is mediated by upregulation of brain-derived neurotrophic factor (BDNF) signaling and that NV-5138 treatment produces rapid synaptic responses in the medial prefrontal cortex. These findings highlight the direct activation of mTORC1 signaling as a potential pharmacological intervention for the treatment of depression.

Authors

Yuto Hasegawa, Xiaolei Zhu, Atsushi Kamiya

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Abstract

Macrophages are tissue-resident or infiltrated immune cells critical for innate immunity, normal tissue development, homeostasis, and repair of damaged tissue. Macrophage function is a sum of their ontogeny, the local environment in which they reside, and the type of injuries or pathogen to which they are exposed. In this Review, we discuss the role of macrophages in the restoration of tissue function after injury, highlighting important questions about how they respond to and modify the local microenvironment to restore homeostasis.

Authors

Satoshi Watanabe, Michael Alexander, Alexander V. Misharin, G.R. Scott Budinger

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Abstract

Excessive excretion of oxalate in the urine results in the formation of calcium oxalate crystals and subsequent kidney stone formation. Severe forms of hyperoxaluria, including genetic forms and those that result from ethylene glycol poisoning, can result in end-stage renal disease. Therapeutic interventions are limited and often rely on dietary intervention. In this issue of the JCI, Le Dudal and colleagues demonstrate that the lactate dehydrogenase 5 inhibitor (LDH5) stiripentol reduces urinary oxalate excretion. Importantly, stiripentol treatment of a single individual with primary hyperoxaluria reduced the urinary oxalate excretion. Together, these results support further evaluation of LDH5 as a therapeutic target for hyperoxaluria.

Authors

Jacob S. Stevens, Qais Al-Awqati

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Abstract

The gut microbiota is crucial for our health, and well-balanced interactions between the host’s immune system and the microbiota are essential to prevent chronic intestinal inflammation, as observed in inflammatory bowel diseases (IBD). A variant in protein tyrosine phosphatase non-receptor type 22 (PTPN22) is associated with reduced risk of developing IBD, but promotes the onset of autoimmune disorders. While the role of PTPN22 in modulating molecular pathways involved in IBD pathogenesis is well studied, its impact on shaping the intestinal microbiota has not been addressed in depth. Here, we demonstrate that mice carrying the PTPN22 variant (619W mice) were protected from acute dextran sulfate sodium (DSS) colitis, but suffered from pronounced inflammation upon chronic DSS treatment. The basal microbiota composition was distinct between genotypes, and DSS-induced dysbiosis was milder in 619W mice than in WT littermates. Transfer of microbiota from 619W mice after the first DSS cycle into treatment-naive 619W mice promoted colitis, indicating that changes in microbial composition enhanced chronic colitis in those animals. This indicates that presence of the PTPN22 variant affects intestinal inflammation by modulating the host’s response to the intestinal microbiota.

Authors

Marianne R. Spalinger, Thomas S.B. Schmidt, Marlene Schwarzfischer, Larissa Hering, Kirstin Atrott, Silvia Lang, Claudia Gottier, Annelies Geirnaert, Christophe Lacroix, Xuezhi Dai, David J. Rawlings, Andrew C. Chan, Christian von Mering, Gerhard Rogler, Michael Scharl

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Abstract

Glial cells have emerged as key players in the central control of energy balance and etiology of obesity. Astrocytes play a central role in neural communication via the release of gliotransmitters. Acyl-CoA–binding protein–derived (ACBP-derived) endozepines are secreted peptides that modulate the GABAA receptor. In the hypothalamus, ACBP is enriched in arcuate nucleus (ARC) astrocytes, ependymocytes, and tanycytes. Central administration of the endozepine octadecaneuropeptide (ODN) reduces feeding and improves glucose tolerance, yet the contribution of endogenous ACBP in energy homeostasis is unknown. We demonstrated that ACBP deletion in GFAP+ astrocytes, but not in Nkx2.1-lineage neural cells, promoted diet-induced hyperphagia and obesity in both male and female mice, an effect prevented by viral rescue of ACBP in ARC astrocytes. ACBP+ astrocytes were observed in apposition with proopiomelanocortin (POMC) neurons, and ODN selectively activated POMC neurons through the ODN GPCR but not GABAA, and suppressed feeding while increasing carbohydrate utilization via the melanocortin system. Similarly, ACBP overexpression in ARC astrocytes reduced feeding and weight gain. Finally, the ODN GPCR agonist decreased feeding and promoted weight loss in ob/ob mice. These findings uncover ACBP as an ARC gliopeptide playing a key role in energy balance control and exerting strong anorectic effects via the central melanocortin system.

Authors

Khalil Bouyakdan, Hugo Martin, Fabienne Liénard, Lionel Budry, Bouchra Taib, Demetra Rodaros, Chloé Chrétien, Éric Biron, Zoé Husson, Daniela Cota, Luc Pénicaud, Stephanie Fulton, Xavier Fioramonti, Thierry Alquier

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Abstract

We studied human T cell repertoire formation using high-throughput T cell receptor β (TCRβ) complementarity-determining region 3 (CDR3) sequencing in immunodeficient mice receiving human hematopoietic stem cells (HSCs) and human thymus grafts. Replicate humanized mice generated diverse and highly divergent repertoires. We observed repertoire narrowing and increased CDR3β sharing during thymocyte selection. Whereas hydrophobicity analysis implicated self-peptides in positive selection of the overall repertoire, positive selection favored shorter shared sequences that had reduced hydrophobicity at positions 6 and 7 of CDR3βs, suggesting weaker interactions with self-peptides than were observed with unshared sequences, possibly allowing escape from negative selection. Sharing was similar between autologous and allogeneic thymi and occurred between different cell subsets. Shared sequences were enriched for allo–cross-reactive CDR3βs and for type 1 diabetes–associated autoreactive CDR3βs. Single-cell TCR sequencing showed increased sharing of CDR3αs compared with CDR3βs between mice. Our data collectively implicate preferential positive selection for shared human CDR3βs that are highly cross-reactive. Although previous studies suggested a role for recombination bias in producing “public” sequences in mice, our study is the first to our knowledge to demonstrate a role for thymic selection. Our results implicate positive selection for promiscuous TCRβ sequences that probably evade negative selection, given their low affinity for self-ligands, in the abundance of “public” human TCRβ sequences.

Authors

Mohsen Khosravi-Maharlooei, Aleksandar Obradovic, Aditya Misra, Keshav Motwani, Markus Holzl, Howard R. Seay, Susan DeWolf, Grace Nauman, Nichole Danzl, Haowei Li, Siu-hong Ho, Robert Winchester, Yufeng Shen, Todd M. Brusko, Megan Sykes

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Abstract

Intrinsically disordered proteins (IDPs) are emerging as attractive drug targets by virtue of their prevalence in various diseases including cancer. Drug development targeting IDPs is challenging because IDPs have dynamic structure features and conventional drug design is not applicable. NUPR1 is an IDP that plays an important role in pancreatic cancer. We previously reported that trifluoperazine (TFP), an antipsychotic agent, was capable of binding to NUPR1 and inhibiting tumor growth. Unfortunately, TFP showed strong central nervous system side effects. In the present work, we undertook a multidisciplinary approach to optimize TFP based on the synergy of computer modeling, chemical synthesis, and a variety of biophysical, biochemical, and biological evaluations. A family of TFP-derived compounds was produced and the most active one, ZZW-115, showed a dose-dependent tumor regression with no neurological effects and an ability to induce cell death mainly by necroptosis. This study opens a new perspective for drug development against IDPs, demonstrating the possibility of successful ligand-based drug design for such challenging targets.

Authors

Patricia Santofimia-Castaño, Yi Xia, Wenjun Lan, Zhengwei Zhou, Can Huang, Ling Peng, Philippe Soubeyran, Adrián Velázquez-Campoy, Olga Abián, Bruno Rizzuti, José L. Neira, Juan Iovanna

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Abstract

Opioid use disorder is associated with the emergence of persistent negative emotional states during drug abstinence that drive compulsive drug taking and seeking. Functional magnetic resonance imaging (fMRI) in rats identified neurocircuits that were activated by stimuli that were previously paired with heroin withdrawal. The activation of amygdala and hypothalamic circuits was related to the degree of heroin dependence, supporting the significance of conditioned negative affect in sustaining compulsive-like heroin seeking and taking and providing neurobiological insights into the drivers of the current opioid crisis.

Authors

Stephanie A. Carmack, Robin J. Keeley, Janaina C. M. Vendruscolo, Emily G. Lowery-Gionta, Hanbing Lu, George F. Koob, Elliot A. Stein, Leandro F. Vendruscolo

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Abstract

Tumor-infiltrating lymphocytes (TILs) are widely associated with positive outcomes, yet carry key indicators of a systemic failed immune response against unresolved cancer. Cancer immunotherapies can reverse their tolerance phenotypes while preserving tumor reactivity and neoantigen specificity shared with circulating immune cells. We performed comprehensive transcriptomic analyses to identify gene signatures common to circulating and TILs in the context of clear cell renal cell carcinoma. Modulated genes also associated with disease outcome were validated in other cancer types. Through comprehensive bioinformatics analyses, we identified practical diagnostic markers and actionable targets of the failed immune response. On circulating lymphocytes, 3 genes (LEF1, FASLG, and MMP9) could efficiently stratify patients from healthy control donors. From their associations with resistance to cancer immunotherapies and microbial infections, we uncovered not only pan-cancer, but pan-pathology, failed immune response profiles. A prominent lymphocytic matrix metallopeptidase cell migration pathway is central to a panoply of diseases and tumor immunogenicity, correlates with multi-cancer recurrence, and identifies a feasible noninvasive approach to pan-pathology diagnoses. The differentially expressed genes we have identified warrant future investigation into the development of their potential in noninvasive precision diagnostics and precision pan-disease immunotherapeutics.

Authors

Anne Monette, Antigoni Morou, Nadia A. Al-Banna, Louise Rousseau, Jean-Baptiste Lattouf, Sara Rahmati, Tomas Tokar, Jean-Pierre Routy, Jean-François Cailhier, Daniel E. Kaufmann, Igor Jurisica, Réjean Lapointe

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Abstract

Prevalence of obesity among infants and children below 5 years of age is rising dramatically, and early childhood obesity is a forerunner of obesity and obesity-associated diseases in adulthood. Childhood obesity is hence one of the most serious public health challenges today. Here, we have identified a mother-to-child lipid signaling that protects from obesity. We have found that breast milk–specific lipid species, so-called alkylglycerol-type (AKG-type) ether lipids, which are absent from infant formula and adult-type diets, maintain beige adipose tissue (BeAT) in the infant and impede the transformation of BeAT into lipid-storing white adipose tissue (WAT). Breast milk AKGs are metabolized by adipose tissue macrophages (ATMs) to platelet-activating factor (PAF), which ultimately activates IL-6/STAT3 signaling in adipocytes and triggers BeAT development in the infant. Accordingly, lack of AKG intake in infancy leads to a premature loss of BeAT and increases fat accumulation. AKG signaling is specific for infants and is inactivated in adulthood. However, in obese adipose tissue, ATMs regain their ability to metabolize AKGs, which reduces obesity. In summary, AKGs are specific lipid signals of breast milk that are essential for healthy adipose tissue development.

Authors

Haidong Yu, Sedat Dilbaz, Jonas Coßmann, Anh Cuong Hoang, Victoria Diedrich, Annika Herwig, Akiko Harauma, Yukino Hoshi, Toru Moriguchi, Kathrin Landgraf, Antje Körner, Christina Lucas, Susanne Brodesser, Lajos Balogh, Julianna Thuróczy, Gopal Karemore, Michael Scott Kuefner, Edwards A. Park, Christine Rapp, Jeffrey Bryant Travers, Tamás Röszer

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Abstract

The study of beige adipose tissue (BeAT) has recently gained popularity because of its potential as a therapeutic target for the treatment of obesity and other metabolic disorders. While BeAT regulation is well understood in adults, the critical signals regulating BeAT during infant development need to be better defined. The bioactive components in breast milk have been primarily studied in the context of immunity. In this issue of the JCI, Yu and Dilbaz et al. identify how a class of breast milk–specific lipid mediators referred to as alkylglycerols (AKGs) maintain BeAT in infants and prevent the transdifferentiation of BeAT into lipid-storing white adipose tissue (WAT).

Authors

Christy M. Gliniak, Philipp E. Scherer

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Abstract

The T cell receptor (TCR) repertoire is diverse, thus allowing recognition of a wide range of pathogens by T cells. In humans, the study of the formation of TCR repertoires is problematic because of the difficulty in performing investigations in vivo. In this issue of the JCI, Khosravi-Maharlooei and colleagues describe a new humanized mouse model that allows direct investigations on this topic. Using high-throughput and single-cell TCR–complementarity-determining region 3 β (TCR-CDR3β) sequencing, the authors were able to demonstrate that human thymic selection is a major driver of TCR sequence sharing, also implicating a preferential selection of shared cross-reactive CDR3βs during repertoire formation.

Authors

Antonio La Cava

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Abstract

Immune cell populations determine the balance between ongoing damage and repair following tissue injury. Cells responding to a tissue-damaged environment have significant bioenergetic and biosynthetic needs. In addition to supporting these needs, metabolic pathways govern the function of pro-repair immune cells, including regulatory T cells and tissue macrophages. In this Review, we explore how specific features of the tissue-damaged environment such as hypoxia, oxidative stress, and nutrient depletion serve as metabolic cues to promote or impair the reparative functions of immune cell populations. Hypoxia, mitochondrial DNA stress, and altered redox balance each contribute to mechanisms regulating the response to tissue damage. For example, hypoxia induces changes in regulatory T cell and macrophage metabolic profiles, including generation of 2-hydroxyglutarate, which inhibits demethylase reactions to modulate cell fate and function. Reactive oxygen species abundant in oxidative environments cause damage to mitochondrial DNA, initiating signaling pathways that likewise control pro-repair cell function. Nutrient depletion following tissue damage also affects pro-repair cell function through metabolic signaling pathways, specifically those sensitive to the redox state of the cell. The study of immunometabolism as an immediate sensor and regulator of the tissue-damaged environment provides opportunities to consider mechanisms that facilitate healthy repair of tissue injury.

Authors

Benjamin D. Singer, Navdeep S. Chandel

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Abstract

The precise regulation of synaptic dopamine (DA) content by the dopamine transporter (DAT) ensures the phasic nature of the DA signal, which underlies the ability of DA to encode reward prediction error, thereby driving motivation, attention, and behavioral learning. Disruptions to the DA system are implicated in a number of neuropsychiatric disorders, including attention deficit hyperactivity disorder (ADHD) and, more recently, Autism Spectrum Disorder (ASD). An ASD-associated de novo mutation in the SLC6A3 gene resulting in a threonine to methionine substitution at site 356 (DAT T356M) was recently identified and has been shown to drive persistent reverse transport of DA (i.e. anomalous DA efflux) in transfected cells and to drive hyperlocomotion in Drosophila melanogaster. A corresponding mutation in the leucine transporter, a DAT-homologous transporter, promotes an outward-facing transporter conformation upon substrate binding, a conformation possibly underlying anomalous dopamine efflux. Here we investigated in vivo the impact of this ASD-associated mutation on DA signaling and ASD-associated behaviors. We found that mice homozygous for this mutation display impaired striatal DA neurotransmission and altered DA-dependent behaviors that correspond with some of the behavioral phenotypes observed in ASD.

Authors

Gabriella E. DiCarlo, Jenny I. Aguilar, Heinrich J.G. Matthies, Fiona E. Harrison, Kyle E. Bundschuh, Alyssa West, Parastoo Hashemi, Freja Herborg, Mattias Rickhag, Hao Chen, Ulrik Gether, Mark T. Wallace, Aurelio Galli

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Abstract

About 1% of all newborns are affected by congenital heart disease (CHD). Recent findings identify aberrantly functioning cilia as a possible source for CHD. Faulty cilia also prevent the development of proper left-right asymmetry and cause heterotaxy, the incorrect placement of visceral organs. Intriguingly, signaling cascades such as mTor that influence mitochondrial biogenesis also affect ciliogenesis, and can cause heterotaxy-like phenotypes in zebrafish. Here, we identify levels of mitochondrial function as a determinant for ciliogenesis and a cause for heterotaxy. We detected reduced mitochondrial DNA content in biopsies of heterotaxy patients. Manipulation of mitochondrial function revealed a reciprocal influence on ciliogenesis and affected cilia-dependent processes in zebrafish, human fibroblasts and Tetrahymena thermophila. Exome analysis of heterotaxy patients revealed an increased burden of rare damaging variants in mitochondria-associated genes as compared to 1000 Genome controls. Knockdown of such candidate genes caused cilia elongation and ciliopathy-like phenotypes in zebrafish, which could not be rescued by RNA encoding damaging rare variants identified in heterotaxy patients. Our findings suggest that ciliogenesis is coupled to the abundance and function of mitochondria. Our data further reveal disturbed mitochondrial function as an underlying cause for heterotaxy-linked CHD and provide a mechanism for unexplained phenotypes of mitochondrial disease.

Authors

Martin D. Burkhalter, Arthi Sridhar, Pedro Sampaio, Raquel Jacinto, Martina S. Burczyk, Cornelia Donow, Max Angenendt, Competence Network for Congenital Heart Defects Investigators, Maja Hempel, Paul Walther, Petra Pennekamp, Heymut Omran, Susana S. Lopes, Stephanie M. Ware, Melanie Philipp

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Abstract

Mobilized peripheral blood has become the primary source of hematopoietic stem and progenitor cells (HSPCs) for stem cell transplantation, with a five-day course of granulocyte colony stimulating factor (G-CSF) as the most common regimen used for HSPC mobilization. The CXCR4 inhibitor, plerixafor, is a more rapid mobilizer, yet not potent enough when used as a single agent, thus emphasizing the need for faster acting agents with more predictable mobilization responses and fewer side effects. We sought to improve hematopoietic stem cell transplantation by developing a new mobilization strategy in mice through combined targeting of the chemokine receptor CXCR2 and the very late antigen 4 (VLA4) integrin. Rapid and synergistic mobilization of HSPCs along with an enhanced recruitment of true HSCs was achieved when a CXCR2 agonist was co-administered in conjunction with a VLA4 inhibitor. Mechanistic studies revealed involvement of CXCR2 expressed on BM stroma in addition to stimulation of the receptor on granulocytes in the regulation of HSPC localization and egress. Given the rapid kinetics and potency of HSPC mobilization provided by the VLA4 inhibitor and CXCR2 agonist combination in mice compared to currently approved HSPC mobilization methods, it represents an exciting potential strategy for clinical development in the future.

Authors

Darja Karpova, Michael P. Rettig, Julie Ritchey, Daniel Cancilla, Stephanie Christ, Leah Gehrs, Ezhilarasi Chendamarai, Moses O. Evbuomwan, Matthew Holt, Jingzhu Zhang, Grazia Abou-Ezzi, Hamza Celik, Eliza Wiercinska, Wei Yang, Feng Gao, Linda G. Eissenberg, Richard F. Heier, Stacy D. Arnett, Marvin J. Meyers, Michael J. Prinsen, David W. Griggs, Andreas Trumpp, Peter G. Ruminski, Dwight M. Morrow, Halvard B. Bonig, Daniel C. Link, John F. DiPersio

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Abstract

Phosphorylation of Dynamin-related protein1 (Drp1) represents an important regulatory mechanism for mitochondrial fission. Here we established the role of Drp1 Serine 600 (S600) phosphorylation on mitochondrial fission in vivo, and assessed the functional consequences of targeted elimination of the Drp1S600 phosphorylation site in progression of diabetic nephropathy (DN). We generated a knockin mouse in which S600 was mutated to alanine (Drp1S600A). We found that diabetic Drp1S600A mice exhibited improved biochemical and histological features of DN along with reduced mitochondrial fission and diminished mitochondrial ROS in vivo. Importantly, we observed that the effect of Drp1S600 phosphorylation on mitochondrial fission in the diabetic milieu was stimulus- but not cell type-dependent. Mechanistically, we showed that mitochondrial fission in high glucose conditions occurs through concomitant binding of phospho-Drp1S600 with mitochondrial fission factor (Mff) and actin-related protein 3 (Arp3), ultimately leading to accumulation of F-actin and Drp1 on the mitochondria. Taken together, these findings establish that a single phosphorylation site in Drp1 can regulate mitochondrial fission and progression of DN in vivo, and highlight the stimulus-specific consequences of Drp1S600 phosphorylation on mitochondrial dynamics.

Authors

Daniel L. Galvan, Jianyin Long, Nathanael Green, Benny H. Chang, Jamie S. Lin, Paul T. Schumacker, Luan D. Truong, Paul Overbeek, Farhad R. Danesh

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Abstract

Oxidative stress is elevated in the recipients of allogeneic hematopoietic transplantation (allo-HCT) and likely contributes to the development of graft-versus-host disease (GVHD). GVHD is characterized by activation, expansion, cytokine production and migration of alloreactive donor T cells, and remains a major cause of morbidity and mortality after allo-HCT. Hence, strategies to limit oxidative stress in GVHD are highly desirable. Thioredoxin1 (Trx1) counteracts oxidative stress by scavenging reactive oxygen species (ROS) and regulating other enzymes that metabolize H2O2. The present study sought to elucidate the role of Trx1 in the pathophysiology of GVHD. Using murine and xenograft models of allogeneic bone marrow transplantation (allo-BMT) and genetic (human Trx1-transgenic, Trx1-Tg) as well as pharmacologic (human recombinant Trx1, RTrx1) strategies; we found that Trx1-Tg donor T cells or administration of the recipients with RTrx1 significantly reduced GVHD severity. Mechanistically, we observed RTrx1 reduced ROS accumulation and cytokine production of mouse and human T cells in response to alloantigen stimulation in vitro. In allo-BMT settings, we found that Trx1-Tg or RTrx1 decreased downstream signaling molecules including NFκB activation and T-bet expression, and reduced proliferation, IFN-γ production and ROS accumulation in donor T cells within GVHD target organs. More importantly, administration of RTrx1 did not impair the graft-versus-leukemia (GVL) effect. Taken together, the current work provides a strong rationale and demonstrates feasibility to target the ROS pathway, which can be readily translated into clinic.

Authors

M. Hanief Sofi, Yongxia Wu, Steven D. Schutt, Min Dai, Anusara Daenthanasanmak, Jessica Heinrichs Voss, Hung Nguyen, David Bastian, Supinya Iamsawat, Shanmugam Panneer Selvam, Chen Liu, Nilanjana Maulik, Besim Ogretmen, Junfei Jin, Shikhar Mehrotra, Xue-Zhong Yu

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May 2019

129 5 cover

May 2019 Issue

On the cover:
Elucidating T cell subtypes in eosinophilic esophagitis

In this issue of the JCI, Wen et al. characterized heterogeneity within 1088 tissue-resident T cells isolated from human esophageal biopsies. They identified 2 distinct subtypes that were enriched in patients with active eosinophilic esophagitis, a T cell–mediated food allergic disease. Coupled with transcriptomic analyses, their observations reveal crucial insights into clinically relevant T cell subtypes, their transcriptomic markers, and pathways that lay the groundwork for tools and models that better account for allergic disease heterogeneity. The cover image spotlights the identification of distinct T cell subtypes in disease, superimposing an isolated T cell over an inflamed eosinophilic esophageal biopsy. Image credit: Chris Woods, Ting Wen, and Marc Rothenberg.

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Jci tm 05

May 2019 JCI This Month

JCI This Month is a digest of the research, reviews, and other features published each month.

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Review Series - More

Allergy

Series edited by Kari Nadeau

The increasing prevalence of allergies worldwide has spurred numerous efforts to better understand risk factors and mechanisms underlying these potentially life-threatening immune responses. Coordinated by Series Editor Kari Nadeau, these reviews address our evolving understanding of the shared and distinct mechanisms underlying allergic diseases of the skin, respiratory system, and gastrointestinal tract. In topics ranging from the molecular and cellular basis of allergy to the influence of the central nervous system, microbiome, and environment, leaders in the field highlight major insights into allergic responses as well as new concepts in treating and preventing allergy.

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