Scientific Resources

A capability for analyzing complex cellular communication among tissues is important in drug discovery and development,and in vitro technologies for doing so are required for human applications. A prominent instance is communication between the gut and the liver,whereby perturbations of one tissue can influence behavior of the other. Here,we present a study on human gut-liver tissue interactions under normal and inflammatory contexts,via an integrative multi-organ platform comprising human liver (hepatocytes and Kupffer cells),and intestinal (enterocytes,goblet cells,and dendritic cells) models. Our results demonstrated long-term (>2 weeks) maintenance of intestinal (e.g.,barrier integrity) and hepatic (e.g.,albumin) functions in baseline interaction. Gene expression data comparing liver in interaction with gut,versus isolation,revealed modulation of bile acid metabolism. Intestinal FGF19 secretion and associated inhibition of hepatic CYP7A1 expression provided evidence of physiologically relevant gut-liver crosstalk. Moreover,significant non-linear modulation of cytokine responses was observed under inflammatory gut-liver interaction; for example,production of CXCR3 ligands (CXCL9,10,11) was synergistically enhanced. RNA-seq analysis revealed significant upregulation of IFNα/β/γ signaling during inflammatory gut-liver crosstalk,with these pathways implicated in the synergistic CXCR3 chemokine production. Exacerbated inflammatory response in gut-liver interaction also negatively affected tissue-specific functions (e.g.,liver metabolism). These findings illustrate how an integrated multi-tissue platform can generate insights useful for understanding complex pathophysiological processes such as inflammatory organ crosstalk. Biotechnol. Bioeng. 2017;114: 2648-2659. textcopyright 2017 Wiley Periodicals,Inc. View Publication

Neural progenitor cell (NPC) migration is an essential process for brain development,adult neurogenesis,and neuroregeneration after brain injury. Stromal cell-derived factor-1 (SDF-1,CXCL12) and its traditional receptor CXCR4 are well known to regulate NPC migration. However,the discovery of CXCR7,a newly identified CXCL12 receptor,adds to the dynamics of the existing CXCL12/CXCR4 pair. Antagonists for either CXCR4 or CXCR7 blocked CXCL12-mediated NPC migration in a transwell chemotaxis assay,suggesting that both receptors are required for CXCL12 action. We derived NPC cultures from Cxcr4 knockout (KO) mice and used transwell and stripe assays to determine the cell migration. NPCs derived from Cxcr4 KO mice polarized and migrated in response to CXCL12 gradient,suggesting that CXCR7 could serve as an independent migration receptor. Furthermore,Cxcr4 KO NPCs transplanted into the adult mouse striatum migrated in response to the adjacent injection of CXCL12,an effect that was blocked by a CXCR7 antagonist,suggesting that CXCR7 also mediates NPC migration in vivo. Molecular mechanism studies revealed that CXCR7 interact with Rac1 in the leading edge of the polarized NPCs in the absence of CXCR4. Both CXCR7 and Rac1 are required for extracellular signal-regulated kinases (ERK) 1/2 activation and subsequent NPC migration,indicating that CXCR7 could serve as a functional receptor in CXCL12-mediated NPC migration independent of CXCR4. Together these results reveal an essential role of CXCR7 for CXCL12-mediated NPC migration that will be important to understand neurogenesis during development and in adulthood. View Publication

Metabolic imaging of brain tumors using (13)C Magnetic Resonance Spectroscopy (MRS) of hyperpolarized [1-(13)C] pyruvate is a promising neuroimaging strategy which,after a decade of preclinical success in glioblastoma (GBM) models,is now entering clinical trials in multiple centers. Typically,the presence of GBM has been associated with elevated hyperpolarized [1-(13)C] lactate produced from [1-(13)C] pyruvate,and response to therapy has been associated with a drop in hyperpolarized [1-(13)C] lactate. However,to date,lower grade gliomas had not been investigated using this approach. The most prevalent mutation in lower grade gliomas is the isocitrate dehydrogenase 1 (IDH1) mutation,which,in addition to initiating tumor development,also induces metabolic reprogramming. In particular,mutant IDH1 gliomas are associated with low levels of lactate dehydrogenase A (LDHA) and monocarboxylate transporters 1 and 4 (MCT1,MCT4),three proteins involved in pyruvate metabolism to lactate. We therefore investigated the potential of (13)C MRS of hyperpolarized [1-(13)C] pyruvate for detection of mutant IDH1 gliomas and for monitoring of their therapeutic response. We studied patient-derived mutant IDH1 glioma cells that underexpress LDHA,MCT1 and MCT4,and wild-type IDH1 GBM cells that express high levels of these proteins. Mutant IDH1 cells and tumors produced significantly less hyperpolarized [1-(13)C] lactate compared to GBM,consistent with their metabolic reprogramming. Furthermore,hyperpolarized [1-(13)C] lactate production was not affected by chemotherapeutic treatment with temozolomide (TMZ) in mutant IDH1 tumors,in contrast to previous reports in GBM. Our results demonstrate the unusual metabolic imaging profile of mutant IDH1 gliomas,which,when combined with other clinically available imaging methods,could be used to detect the presence of the IDH1 mutation in vivo. View Publication

Macrophages are a source of both proinflammatory and restorative functions in damaged tissue through complex dynamic phenotypic changes. Here,we sought to determine whether monocyte-derived macrophages (MDMs) contribute to recovery after acute sterile brain injury. By profiling the transcriptional dynamics of MDMs in the murine brain after experimental intracerebral hemorrhage (ICH),we found robust phenotypic changes in the infiltrating MDMs over time and demonstrated that MDMs are essential for optimal hematoma clearance and neurological recovery. Next,we identified the mechanism by which the engulfment of erythrocytes with exposed phosphatidylserine directly modulated the phenotype of both murine and human MDMs. In mice,loss of receptor tyrosine kinases AXL and MERTK reduced efferocytosis of eryptotic erythrocytes and hematoma clearance,worsened neurological recovery,exacerbated iron deposition,and decreased alternative activation of macrophages after ICH. Patients with higher circulating soluble AXL had poor 1-year outcomes after ICH onset,suggesting that therapeutically augmenting efferocytosis may improve functional outcomes by both reducing tissue injury and promoting the development of reparative macrophage responses. Thus,our results identify the efferocytosis of eryptotic erythrocytes through AXL/MERTK as a critical mechanism modulating macrophage phenotype and contributing to recovery from ICH. View Publication

The ability of high-risk neuroblastoma to survive unfavorable growth conditions and multimodal therapy has produced an elusive childhood cancer with remarkably poor prognosis. A novel phenomenon enabling neuroblastoma to survive selection pressure is its capacity for reversible adaptive plasticity. This plasticity allows cells to transition between highly proliferative anchorage dependent (AD) and slow growing,anoikis-resistant anchorage independent (AI) phenotypes. Both phenotypes are present in established mouse and human tumors. The differential gene expression profile of the two cellular phenotypes in the mouse Neuro2a cell line delineated pathways of proliferation in AD cells or tyrosine kinase activation/ apoptosis inhibition in AI cells. A 20 fold overexpression of inhibitor of differentiation 2 (Id2) was identified in AD cells while up-regulation of genes involved in anoikis resistance like PI3K/Akt,Erk,Bcl2 and integrins was observed in AI cells. Similarly,differential expression of Id2 and other genes of interest were also observed in the AD and AI phenotypes of human neuroblastoma cell lines,SK-N-SH and IMR-32; as well as in primary human tumor specimens. Forced down-regulation of Id2 in AD cells or overexpression in AI cells induced the cells to gain characteristics of the other phenotype. Id2 binds both TGFβ and Smad2/3 and appears critical for maintaining the proliferative phenotype at least partially through negative regulation of the TGFβ/Smad pathway. Simultaneously targeting the differential molecular pathways governing reversible adaptive plasticity resulted in 50% cure of microscopic disease and delayed tumor growth in established mouse neuroblastoma tumors. We present a mechanism that accounts for reversible adaptive plasticity and a molecular basis for combined targeted therapies in neuroblastoma. View Publication

BACKGROUND UBQLN2 mutations have recently been associated with familial forms of amyotrophic lateral sclerosis (ALS) and ALS-dementia. UBQLN2 encodes for ubiquilin-2,a member of the ubiquitin-like protein family which facilitates delivery of ubiquitinated proteins to the proteasome for degradation. To study the potential role of ubiquilin-2 in ALS,we used recombinant adeno-associated viral (rAAV) vectors to express UBQLN2 and three of the identified ALS-linked mutants (P497H,P497S,and P506T) in primary neuroglial cultures and in developing neonatal mouse brains. RESULTS In primary cultures rAAV2/8-mediated expression of UBQLN2 mutants resulted in inclusion bodies and insoluble aggregates. Intracerebroventricular injection of FVB mice at post-natal day 0 with rAAV2/8 expressing wild type or mutant UBQLN2 resulted in widespread,sustained expression of ubiquilin-2 in brain. In contrast to wild type,mutant UBQLN2 expression induced significant pathology with large neuronal,cytoplasmic inclusions and ubiquilin-2-positive aggregates in surrounding neuropil. Ubiquilin-2 inclusions co-localized with ubiquitin,p62/SQSTM,optineurin,and occasionally TDP-43,but were negative for α-synuclein,neurofilament,tau,and FUS. Mutant UBLQN2 expression also resulted in Thioflavin-S-positive inclusions/aggregates. Mice expressing mutant forms of UBQLN2 variably developed a motor phenotype at 3-4 months,including nonspecific clasping and rotarod deficits. CONCLUSIONS These findings demonstrate that UBQLN2 mutants (P497H,P497S,and P506T) induce proteinopathy and cause behavioral deficits,supporting a toxic" gain-of-function which may contribute to ALS pathology. These data establish also that our rAAV model can be used to rapidly assess the pathological consequences of various UBQLN2 mutations and provides an agile system to further interrogate the molecular mechanisms of ubiquilins in neurodegeneration. View Publication

Langerhans cell histiocytosis (LCH) is a rare disease with an unknown etiology characterized by heterogeneous lesions containing CD207+CD1a+ cells that can arise in almost any tissue and cause significant morbidity and mortality. Precursors of pathological Langerhans cells have yet to be defined. Our aim was to identify circulating CD207+CD1a+ cells and their inducers in LCH. Expression of CD207 and CD1a in the blood myeloid compartment as well as thymic stromal lymphopoietin (TSLP) and transforming growth factor β (TGF-β) plasma levels were measured in 22 pediatric patients with active disease (AD) or nonactive disease (NAD). In patients with AD vs those with NAD,the myeloid compartment showed an increased CD11b (CD11bhigh plus CD11b+) fraction (39.7 ± 3.6 vs 18.6 ± 1.9),a higher percentage of circulating CD11bhighCD11c+CD207+ cells (44.5 ± 11.3 vs 3.2 ± 0.5),and the presence of CD11chighCD207+CD1a+ cells (25.0 ± 9.1 vs 2.3 ± 0.5). Blood CD207+CD1a+ cells were not observed in adult controls or umbilical cord. Increased TSLP and TGF-β levels were detected in patients with AD. Interestingly,plasma from patients with AD induces CD207 expression on CD14+ monocytes. We conclude that CD207+CD1a+ cells are circulating in patients with active LCH,and TSLP and TGF-β are potential drivers of Langerhans-like cells in vivo. View Publication

Mucosal Langerhans cells (LCs) originate from pre-dendritic cells and monocytes. However,the mechanisms involved in their in situ development remain unclear. Here,we demonstrate that the differentiation of murine mucosal LCs is a two-step process. In the lamina propria,signaling via BMP7-ALK3 promotes translocation of LC precursors to the epithelium. Within the epithelium,TGF-β1 finalizes LC differentiation,and ALK5 is crucial to this process. Moreover,the local microbiota has a major impact on the development of mucosal LCs,whereas LCs in turn maintain mucosal homeostasis and prevent tissue destruction. These results reveal the differential and sequential role of TGF-β1 and BMP7 in LC differentiation and highlight the intimate interplay of LCs with the microbiota. View Publication

Exposure to cigarette smoke causes a multitude of pathological changes leading to tissue damage and disease. Quantifying such changes in highly differentiated in vitro human tissue models may assist in evaluating the toxicity of tobacco products. In this methods development study,well-differentiated human air-liquid-interface (ALI) in vitro airway tissue models were used to assess toxicological endpoints relevant to tobacco smoke exposure. Whole mainstream smoke solutions (WSSs) were prepared from 2 commercial cigarettes (R60 and S60) that differ in smoke constituents when machine-smoked under International Organization for Standardization conditions. The airway tissue models were exposed apically to WSSs 4-h per day for 1-5 days. Cytotoxicity,tissue barrier integrity,oxidative stress,mucin secretion,and matrix metalloproteinase (MMP) excretion were measured. The treatments were not cytotoxic and had marginal effects on tissue barrier properties; however,other endpoints responded in time- and dose-dependent manners,with the R60 resulting in higher levels of response than the S60 for many endpoints. Based on the lowest effect dose,differences in response to the WSSs were observed for mucin induction and MMP secretion. Mitigation of mucin induction by cotreatment of cultures with N-acetylcysteine suggests that oxidative stress contributes to mucus hypersecretion. Overall,these preliminary results suggest that quantifying disease-relevant endpoints using ALI airway models is a potential tool for tobacco product toxicity evaluation. Additional research using tobacco samples generated under smoking machine conditions that more closely approximate human smoking patterns will inform further methods development. View Publication

A major challenge in developing gene-based therapies for airway diseases such as cystic fibrosis (CF) is sustaining therapeutic levels of transgene expression over time. This is largely due to airway epithelial cell turnover and the host immunogenicity to gene delivery vectors. Modern gene editing tools and delivery vehicles hold great potential for overcoming this challenge. There is currently not much known about how to deliver genes into airway stem cells,of which basal cells are the major type in human airways. In this study,helper-dependent adenoviral (HD-Ad) vectors were delivered to mouse and pig airways via intranasal delivery,and direct bronchoscopic instillation,respectively. Vector transduction was assessed by immunostaining of lung tissue sections,which revealed that airway basal cells of mice and pigs can be targeted in vivo. In addition,efficient transduction of primary human airway basal cells was verified with an HD-Ad vector expressing green fluorescent protein. Furthermore,we successfully delivered the human CFTR gene to airway basal cells from CF patients,and demonstrated restoration of CFTR channel activity following cell differentiation in air-liquid interface culture. Our results provide a strong rationale for utilizing HD-Ad vectors to target airway basal cells for permanent gene correction of genetic airway diseases. View Publication

A current model posits that cofilin-dependent actin severing negatively impacts dendritic spine volume. Studies suggested that increased cofilin activity underlies activity-dependent spine shrinkage,and that reduced cofilin activity induces activity-dependent spine growth. We suggest instead that both types of structural plasticity correlate with decreased cofilin activity. However,the mechanism of inhibition determines the outcome for spine morphology. RNAi in rat hippocampal cultures demonstrates that cofilin is essential for normal spine maintenance. Cofilin-F-actin binding and filament barbed-end production decrease during the early phase of activity-dependent spine shrinkage; cofilin concentration also decreases. Inhibition of the cathepsin B/L family of proteases prevents both cofilin loss and spine shrinkage. Conversely,during activity-dependent spine growth,LIM kinase stimulates cofilin phosphorylation,which activates phospholipase D-1 to promote actin polymerization. These results implicate novel molecular mechanisms and prompt a revision of the current model for how cofilin functions in activity-dependent structural plasticity. View Publication

Increasing evidence suggests that cellular stress may underlie mood disorders such as bipolar disorder and major depression,particularly as lithium and its targets can protect against neuronal cell death. Here we describe N-methyl-D-aspartate (NMDA)-induced filamentous actin reorganization (NIFAR) as a useful in-vitro model for studying acute neurocellular stress and investigating the effects of mood stabilizers. Brief incubation of cultured neurons with NMDA (50 µM,5 min) induces marked reorganization of F-actin within the somatodendritic domain of a majority of neurons. During NIFAR,F-actin is rapidly depleted from dendritic spines and aberrantly aggregates within the dendrite shaft. The widely used mood stabilizer lithium chloride prevented NIFAR in a time-dependent and dose-dependent manner,consistent with its known efficacy in treating bipolar disorder. Inhibitors of the lithium target glycogen synthase kinase 3 and its upstream activator phosphoinositide-3-kinase also prevented NIFAR. The antidepressant compounds imipramine and fluoxetine also attenuated NIFAR. These findings have potential relevance to neuropsychiatric diseases characterized by excessive glutamate receptor activity and synaptotoxicity. We propose that protection of the dendritic actin cytoskeleton may be a common mechanism shared by various mood stabilizers. View Publication