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1.  A combination HIV reporter virus system for measuring post-entry event efficiency and viral outcome in primary CD4+ T cell subsets 
Journal of virological methods  2013;195:164-169.
Fusion between the viral membrane of human immunodeficiency virus (HIV) and the host cell marks the end of the HIV entry process and the beginning of a series of post-entry events including uncoating, reverse transcription, integration, and viral gene expression. The efficiency of post-entry events can be modulated by cellular factors including viral restriction factors and can lead to several distinct outcomes: productive, latent, or abortive infection. Understanding host and viral proteins impacting post-entry event efficiency and viral outcome is critical for strategies to reduce HIV infectivity and to optimize transduction of HIV-based gene therapy vectors. Here, we report a combination reporter virus system measuring both membrane fusion and viral promoter-driven gene expression. This system enables precise determination of unstimulated primary CD4+ T cell subsets targeted by HIV, the efficiency of post-entry viral events, and viral outcome and is compatible with high-throughput screening and cell-sorting methods.
PMCID: PMC3982591  PMID: 24025341
HIV; reporter virus; fusion; LTR; gene expression; post-entry event efficiency; outcome
2.  Transcriptional impact of organophosphate and metal mixtures on olfaction: Copper dominates the chlorpyrifos-induced response in adult zebrafish 
Chemical exposures in fish have been linked to loss of olfaction leading to an inability to detect predators and prey and decreased survival. However, the mechanisms underlying olfactory neurotoxicity are not well characterized, especially in environmental exposures which involve chemical mixtures. We used zebrafish to characterize olfactory transcriptional responses by two model olfactory inhibitors, the pesticide chlorpyrifos (CPF) and mixtures of CPF with the neurotoxic metal copper (Cu). Microarray analysis was performed on RNA from olfactory tissues of zebrafish exposed to CPF alone or to a mixture of CPF and Cu. Gene expression profiles were analyzed using Principal Component Analysis and hierarchical clustering, whereas gene set analysis was used to identify biological themes in the microarray data. Microarray results were confirmed by real-time PCR on genes serving as potential biomarkers of olfactory injury. In addition, we mined our previously published Cu-induced zebrafish olfactory transcriptional response database (Tilton et al., 2008) for the purposes of discriminating pathways of olfaction impacted by either the individual agents or the CPF-Cu mixture transcriptional signatures. CPF exposure altered the expression of gene pathways associated with cellular morphogenesis and odorant binding, but not olfactory signal transduction, a known olfactory pathway for Cu. The mixture profiles shared genes from the Cu and CPF datasets, whereas some genes were altered only by the mixtures. The transcriptional signature of the mixtures was more similar to that in zebrafish exposed to Cu alone then for CPF. In conclusion, exposure to a mixture containing a common environmental metal and pesticide causes a unique transcriptional signature that is heavily influenced by the metal, even when organophosphate predominates. Our findings support using zebrafish microarray analysis to elucidate mechanisms of olfactory loss and to identify the components of mixtures which most strongly contribute to olfactory injury.
PMCID: PMC3991301  PMID: 21356183
copper; chlorpyrifos; organophosphate pesticide; zebrafish; olfaction; toxicity; mixtures
3.  Transcriptional biomarkers and mechanisms of copper-induced olfactory injury in zebrafish. 
Environmental science & technology  2008;42(24):9404-9411.
Metals such as copper disrupt olfactory function in fish. Unfortunately, little is understood of the molecular consequences of copper olfactory impairment, thus hindering the development of relevant diagnostic tools of olfactory injury. To address this critical data gap, we analyzed gene expression within olfactory tissues of adult zebrafish exposed to CuCl2 (6, 16, 40 ppb) for 24 hrs. Transcriptional markers of copper impairment within the entire olfactory system were identified and specific genes of interest (e.g. S100a, parvalbumin 8, olfactory marker protein, and calbindin 2-like protein) were confirmed with quantitative real-time PCR. In addition, we performed gene set analysis (GSA) using both a-priori and custom pathways of gene sets specifically targeting the olfactory signal transduction (OST) pathway. These analyses revealed down-regulated gene sets related to calcium channels and ion transport, g-proteins, and olfactory receptors. Collectively, these data demonstrate that copper causes a depression of transcription of key genes within the OST pathway and elsewhere within olfactory tissues, likely resulting in an olfactory system less responsive to odorants. Further, these data provide a mechanistic explanation in support of earlier studies of functional olfactory impairment in fish following copper exposure.
PMCID: PMC3321378  PMID: 19174923
4.  Automated direct antimicrobial susceptibility testing of microscopically screened urine cultures. 
Journal of Clinical Microbiology  1980;11(2):157-161.
Two screening methods for urine microbiology are proposed: one in which the Gram-stained smear is used to detect significant bacteriuria, and another in which Autobac antibiotic susceptibility tests are performed directly on positive urine samples. Results on 1,350 specimens indicated that an average of 18 bacteria per oil immersion field were observed in the urine of patients with significant bacteriuria, and an average of less than 1 bacterium per oil immersion field was found in the urine of patients without significant bacteriuria. Direct susceptibility testing by Autobac proved to be rapid (3 h versus 24 h) and reliable (0.5 to 1.2% discrepancies).
PMCID: PMC273344  PMID: 6766953
5.  Impaired Transcriptional Response of the Murine Heart To Cigarette Smoke in the Setting of High Fat Diet and Obesity 
Chemical research in toxicology  2013;26(7):1034-1042.
Smoking and obesity are each well-established risk factors for cardiovascular heart disease, which together impose earlier onset and greater severity of disease. To identify early signaling events in the response of the heart to cigarette smoke exposure within the setting of obesity, we exposed normal weight and high fat diet-induced obese (DIO) C57BL/6 mice to repeated inhaled doses of mainstream (MS) or sidestream (SS) cigarette smoke administered over a two week period, monitoring effects on both cardiac and pulmonary transcriptomes. MS smoke (250 µg wet total particulate matter (WTPM)/L, 5h/day) exposures elicited robust cellular and molecular inflammatory responses in the lung with 1466 differentially expressed pulmonary genes (p<0.01) in normal weight animals, and a muchattenuated response (463 genes) in the hearts of the same animals. In contrast, exposures to SS smoke (85 µg WTPM/L) with an equivalent CO concentration as that of MS smoke (~250 CO ppm), induced a weak pulmonary response (328 genes), but an extensive cardiac response (1590 genes). SS smoke, and to a lesser extent MS smoke preferentially elicited hypoxia- and stress-responsive genes as well as genes predicting early changes of vascular smooth muscle and endothelium, precursors of cardiovascular disease. The most sensitive smoke-induced cardiac transcriptional changes of normal weight mice were largely absent in DIO mice after smoke exposure, while genes involved in fatty acid utilization were unaffected. At the same time, smoke exposure suppressed multiple proteome maintenance genes induced in the hearts of DIO mice. Together these results underscore the sensitivity of the heart to SS smoke and reveal adaptive responses in healthy individuals that are absent in the setting of high fat diet and obesity.
PMCID: PMC4234196  PMID: 23786483
heart transcriptome; mainstream cigarette smoke; sidestream cigarette smoke; hypoxia; peroxisomal proliferator-activated receptor-α; high fat diet; obesity
6.  Three human cell types respond to multi-walled carbon nanotubes and titanium dioxide nanobelts with cell-specific transcriptomic and proteomic expression patterns 
Nanotoxicology  2013;8(5):533-548.
The growing use of engineered nanoparticles (NPs) in commercial and medical applications raises the urgent need for tools that can predict NP toxicity. We conducted global transcriptome and proteome analyses of three human cell types, exposed to two high aspect ratio NP types, to identify patterns of expression that might indicate high vs. low NP toxicity. Three cell types representing the most common routes of human exposure to NPs, including macrophage like (THP-1), small airway epithelial (SAE), and intestinal (Caco-2/HT29-MTX) cells, were exposed to TiO2 nanobelts (TiO2-NB; high toxicity) and multi-walled carbon nanotubes (MWCNT; low toxicity) at low (10 μg/ml) and high (100 μg/ml) concentrations for 1 and 24 h. Unique patterns of gene and protein expressions were identified for each cell type, with no differentially expressed (p<0.05, 1.5-fold change) genes or proteins overlapping across all three cell types. While unique to each cell-type, the early response was primarily independent of NP type, showing similar expression patterns in response to both TiO2-NB and MWCNT. The early response might therefore indicate a general response to insult. In contrast, the 24 h response was unique to each NP type. The most significantly (p<0.05) enriched biological processes in THP-1 cells indicated TiO2-NB regulation of pathways associated with inflammation, apoptosis, cell cycle arrest, DNA replication stress and genomic instability, while MWCNT regulated pathways indicating increased cell proliferation, DNA repair and anti-apoptosis. These two distinct sets of biological pathways might therefore underlie cellular responses to high and low NP toxicity, respectively.
PMCID: PMC4226242  PMID: 23659652
biological pathway; biological network; differential gene regulation; differential protein regulation; high aspect ratio nanomaterial
7.  CD4+ Memory Stem Cells Are Infected by HIV-1 in a Manner Regulated in Part by SAMHD1 Expression 
Journal of Virology  2014;88(9):4976-4986.
CD4+ and CD8+ memory T cells with stem cell-like properties (TSCM cells) have been identified in mice, humans, and nonhuman primates and are being investigated for antitumor and antiviral vaccines and immunotherapies. Whether CD4+ TSCM cells are infected by human immunodeficiency virus (HIV) was investigated by using a combination HIV reporter virus system in vitro and by direct staining for HIV p24 antigen ex vivo. A proportion of TSCM cells were found to express the HIV coreceptors CCR5 and CXCR4 and were infected by HIV both in vitro and in vivo. Analysis of viral outcome following fusion using the combination reporter virus system revealed that TSCM cells can become productively or latently infected, although the vast majority of TSCM cells are abortively infected. Knockdown of the HIV restriction factor SAMHD1 using Vpx-containing simian immunodeficiency virus (SIV) virion-like particles enhanced the productive infection of TSCM cells, indicating that SAMHD1 contributes to abortive infection in these cells. These results demonstrate that CD4+ TSCM cells are targets for HIV infection, that they become productively or latently infected at low levels, and that SAMHD1 expression promotes abortive infection of this important memory cell subset.
IMPORTANCE Here we demonstrate the susceptibility of CD4+ memory stem cells (TSCM cells) to infection by HIV in vitro and in vivo, provide an in-depth analysis of coreceptor expression, demonstrate the infection of naïve and memory CD4+ T cell subsets with both CCR5- and CXCR4-tropic HIV, and also perform outcome analysis to calculate the percentage of cells that are productively, latently, or abortively infected. Through these outcome studies, we determined that the vast majority of TSCM cells are abortively infected by HIV, and we demonstrate that knockdown of SAMHD1 significantly increases the frequency of infection of this CD4+ T cell subset, indicating that SAMHD1 is an active restriction factor in TSCM cells.
PMCID: PMC3993838  PMID: 24554663
8.  Comparative iron oxide nanoparticle cellular dosimetry and response in mice by the inhalation and liquid cell culture exposure routes 
Toxicity testing the rapidly growing number of nanomaterials requires large scale use of in vitro systems under the presumption that these systems are sufficiently predictive or descriptive of responses in in vivo systems for effective use in hazard ranking. We hypothesized that improved relationships between in vitro and in vivo models of experimental toxicology for nanomaterials would result from placing response data in vitro and in vivo on the same dose scale, the amount of material associated with cells.
Balb/c mice were exposed nose-only to an aerosol (68.6 nm CMD, 19.9 mg/m3, 4 hours) generated from of 12.8 nm superparamagnetic iron oxide particles (SPIO). Target cell doses were calculated, histological evaluations conducted, and biomarkers of response were identified by global transcriptomics. Representative murine epithelial and macrophage cell types were exposed in vitro to the same material in liquid suspension for four hours and levels of nanoparticle regulated cytokine transcripts identified in vivo were quantified as a function of measured nanoparticle cellular dose.
Target tissue doses of 0.009-0.4 μg SPIO/cm2 in lung led to an inflammatory response in the alveolar region characterized by interstitial inflammation and macrophage infiltration. In vitro, higher target tissue doses of ~1.2-4 μg SPIO/ cm2 of cells were required to induce transcriptional regulation of markers of inflammation, CXCL2 & CCL3, in C10 lung epithelial cells. Estimated in vivo macrophage SPIO nanoparticle doses ranged from 1-100 pg/cell, and induction of inflammatory markers was observed in vitro in macrophages at doses of 8-35 pg/cell.
Application of target tissue dosimetry revealed good correspondence between target cell doses triggering inflammatory processes in vitro and in vivo in the alveolar macrophage population, but not in the epithelial cells of the alveolar region. These findings demonstrate the potential for target tissue dosimetry to enable the more quantitative comparison of in vitro and in vivo systems and advance their use for hazard assessment and extrapolation to humans. The mildly inflammogentic cellular doses experienced by mice were similar to those calculated for humans exposed to the same material at the existing permissible exposure limit of 10 mg/m3 iron oxide (as Fe).
Electronic supplementary material
The online version of this article (doi:10.1186/s12989-014-0046-4) contains supplementary material, which is available to authorized users.
PMCID: PMC4200214  PMID: 25266609
Magnetic particle detection; Nano-aerosol; In vivo testing; Lung deposition; Nanoparticle; Dosimetry; Extrapolation
9.  Bilateral Choroidal Metastasis from Non-Small Cell Lung Cancer 
Breast and lung cancers are the most common primary neoplasms to manifest with choroidal metastases. The incidence of choroidal metastases from metastatic lung cancer was reported to be 2–6.7%. We report a case of bilateral choroidal metastasis from non-small cell lung cancer. A 59-year-old Caucasian female patient, never a smoker, was diagnosed with stage IV lung adenocarcinoma metastatic to the pleura, bones, and the brain. Her initial scan of the chest showed innumerable soft tissue nodules and mediastinal adenopathy compatible with metastatic disease. Her initial brain MRI showed numerous small enhancing lesions consistent with extensive disease. Unfortunately, during her follow-up visits, she presented with bulge on her left eye. Simultaneously, her follow-up chest scan showed increase in the size of the lung nodules. She continued to have a reasonable performance status at that time, except for mild increase in her dyspnea. The choroidal metastases require a multidisciplinary care and should be among the differential patients with malignancy who present with ocular symptoms.
PMCID: PMC4180387  PMID: 25295203
10.  Dysregulation of Macrophage Activation Profiles by Engineered Nanoparticles 
ACS nano  2013;7(8):6997-7010.
Although the potential human health impacts from exposure to engineered nanoparticles (ENPs) are uncertain, past epidemiological studies have established correlations between exposure to ambient air pollution particulates and the incidence of pneumonia and lung infections. Using amorphous silica and superparamagnetic iron oxide (SPIO) as model high production volume ENPs, we examined how macrophage activation by bacterial lipopolysaccharide (LPS) or the lung pathogen Streptococcus pneumoniae is altered by ENP pre-treatment. Neither silica nor SPIO treatment elicited direct cytotoxic or pro-inflammatory effects in bone marrow-derived macrophages. However, pre-treatment of macrophages with SPIO caused extensive reprogramming of nearly 500 genes regulated in response to LPS challenge, hallmarked by exaggerated activation of oxidative stress response pathways and suppressed activation of both pro- and anti-inflammatory pathways. Silica pre-treatment altered regulation of only 67 genes, but there was strong correlation with gene sets affected by SPIO. Macrophages exposed to SPIO displayed a phenotype suggesting an impaired ability to transition from a M1 to M2-like activation state, characterized by suppressed IL-10 induction, enhanced TNFα production, and diminished phagocytic activity toward S. pneumoniae. Studies in macrophages deficient in scavenger receptor A (SR-A) showed SR-A participates in cell uptake of both the ENPs and S. pneumonia, and co-regulates the anti-inflammatory IL-10 pathway. Thus, mechanisms for dysregulation of innate immunity exist by virtue that common receptor recognition pathways are used by some ENPs and pathogenic bacteria, although the extent of transcriptional reprogramming of macrophage function depends on the physicochemical properties of the ENP after internalization. Our results also illustrate that biological effects of ENPs may be indirectly manifested only after challenging normal cell function. Nanotoxicology screening strategies should therefore consider how exposure to these materials alters susceptibility to other environmental exposures.
PMCID: PMC3756554  PMID: 23808590
nanotoxicology; macrophage; iron oxide; amorphous silica; Streptococcus pneumoniae; lipopolysaccharide; scavenger receptor
11.  Oxidative Stress Induces Endothelial Cell Senescence via Downregulation of Sirt6 
BioMed Research International  2014;2014:902842.
Accumulating evidence has shown that diabetes accelerates aging and endothelial cell senescence is involved in the pathogenesis of diabetic vascular complications, including diabetic retinopathy. Oxidative stress is recognized as a key factor in the induction of endothelial senescence and diabetic retinopathy. However, specific mechanisms involved in oxidative stress-induced endothelial senescence have not been elucidated. We hypothesized that Sirt6, which is a nuclear, chromatin-bound protein critically involved in many pathophysiologic processes such as aging and inflammation, may have a role in oxidative stress-induced vascular cell senescence. Measurement of Sirt6 expression in human endothelial cells revealed that H2O2 treatment significantly reduced Sirt6 protein. The loss of Sirt6 was associated with an induction of a senescence phenotype in endothelial cells, including decreased cell growth, proliferation and angiogenic ability, and increased expression of senescence-associated β-galactosidase activity. Additionally, H2O2 treatment reduced eNOS expression, enhanced p21 expression, and dephosphorylated (activated) retinoblastoma (Rb) protein. All of these alternations were attenuated by overexpression of Sirt6, while partial knockdown of Sirt6 expression by siRNA mimicked the effect of H2O2. In conclusion, these results suggest that Sirt6 is a critical regulator of endothelial senescence and oxidative stress-induced downregulation of Sirt6 is likely involved in the pathogenesis of diabetic retinopathy.
PMCID: PMC4138737  PMID: 25162034
12.  HIV: Cell Binding and Entry 
The first step of the human immunodeficiency virus (HIV) replication cycle—binding and entry into the host cell—plays a major role in determining viral tropism and the ability of HIV to degrade the human immune system. HIV uses a complex series of steps to deliver its genome into the host cell cytoplasm while simultaneously evading the host immune response. To infect cells, the HIV protein envelope (Env) binds to the primary cellular receptor CD4 and then to a cellular coreceptor. This sequential binding triggers fusion of the viral and host cell membranes, initiating infection. Revealing the mechanism of HIV entry has profound implications for viral tropism, transmission, pathogenesis, and therapeutic intervention. Here, we provide an overview into the mechanism of HIV entry, provide historical context to key discoveries, discuss recent advances, and speculate on future directions in the field.
The HIV envelope protein binds to the host cell receptor CD4 and then to a cellular coreceptor. This triggers fusion of the viral and host cell membranes, initiating infection.
PMCID: PMC3405824  PMID: 22908191
13.  TWEAK/Fn14 Pathway Is a Novel Mediator of Retinal Neovascularization 
Retinal neovascularization (NV) is a major cause of vision loss in ischemia-induced retinopathy. Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor inducible–14 (Fn14), have been implicated in angiogenesis, but their role in retinal diseases is unknown. The goal of this study was to investigate the role of TWEAK/Fn14 pathway in retinal NV.
Studies were performed in a mouse model of oxygen-induced retinopathy (OIR) and in primary human retinal microvascular endothelial cells (HRMECs). Hyperoxia treatment was initiated on postnatal day (P)14. Immunohistochemistry and quantitative PCR (qPCR) were used to assess retinal vascular changes in relation to expression of Fn14 and TWEAK.
Fibroblast growth factor–inducible 14 mRNA was prominently increased from P13 to P17 in OIR retinas, whereas TWEAK level was slightly decreased. These alterations were normalized by hyperoxia treatment and were more striking in isolated retinal vessels. There was a discernible shift in the immunoreactivity of Fn14 and TWEAK from the neuronal layers in the healthy retina to the neovascular tufts in that of OIR. Blockade of TWEAK/Fn14 significantly prevented retinal NV while slightly accelerated revascularization. In contrast, activation of Fn14 positively regulated survival pathways in the B-cell lymphoma-2 (Bcl2) family and robustly enhanced HRMEC survival. Furthermore, gene analysis revealed the regulatory region of Fn14 gene contains several conserved hypoxia inducible factor (HIF)-1α binding sites. Overexpression of HIF-1α prominently induced Fn14 expression in HRMECs.
We found that the TNF-like weak inducer of apoptosis (TWEAK)/fibroblast growth factor inducible–14 (Fn14) pathway is involved in the development of pathologic retinal neovascularization. Hypoxia inducible factor–1α is likely implicated in the upregulation of Fn14.
We found that the TNF-like weak inducer of apoptosis (TWEAK)/fibroblast growth factor inducible–14 (Fn14) pathway is involved in the development of pathologic retinal neovascularization.
PMCID: PMC3920863  PMID: 24408972
ischemia-induced retinopathy; neovascularization; TWEAK; Fn14; retina
14.  Structurally distinct polycyclic aromatic hydrocarbons induce differential transcriptional responses in developing zebrafish 
Toxicology and applied pharmacology  2013;272(3):656-670.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment as components of fossil fuels and by-products of combustion. These multi-ring chemicals differentially activate the Aryl Hydrocarbon Receptor (AHR) in a structurally dependent manner, and induce toxicity via both AHR-dependent and-independent mechanisms. PAH exposure is known to induce developmental malformations in zebrafish embryos, and recent studies have shown cardiac toxicity induced by compounds with low AHR affinity. Unraveling the potentially diverse molecular mechanisms of PAH toxicity is essential for understanding the hazard posed by complex PAH mixtures present in the environment. We analyzed transcriptional responses to PAH exposure in zebrafish embryos exposed to benz(a)anthracene (BAA), dibenzothiophene (DBT) and pyrene (PYR) at concentrations that induced developmental malformations by 120 hours post-fertilization (hpf). Whole genome microarray analysis of mRNA expression at 24 and 48 hpf identified genes that were differentially regulated over time and in response to the three PAH structures. PAH body burdens were analyzed at both time points using GC-MS, and demonstrated differences in PAH uptake into the embryos. This was important for discerning dose-related differences from those that represented unique molecular mechanisms. While BAA misregulated the least number of transcripts, it caused strong induction of cyp1a and other genes known to be downstream of the AHR, which were not induced by the other two PAHs. Analysis of functional roles of misregulated genes and their predicted regulatory transcription factors also distinguished the BAA response from regulatory networks disrupted by DBT and PYR exposure. These results indicate that systems approaches can be used to classify the toxicity of PAHs based on the networks perturbed following exposure, and may provide a path for unraveling the toxicity of complex PAH mixtures.
PMCID: PMC4098828  PMID: 23656968
toxicity; AHR; microarray; dibenzothiophene; pyrene; benz(a)anthracene; network analysis
15.  Global gene expression analysis reveals pathway differences between teratogenic and non-teratogenic exposure concentrations of bisphenol A and 17β-estradiol in embryonic zebrafish 
Transient developmental exposure to 0.1 μM bisphenol A (BPA) results in larval zebrafish hyperactivity and learning impairments in the adult, while exposure to 80 μM BPA results in teratogenic responses, including craniofacial abnormalities and edema. The mode of action underlying these effects is unclear. We used global gene expression analysis to identify candidate genes and signaling pathways that mediate BPA’s developmental toxicity in zebrafish. Exposure concentrations were selected and anchored to the positive control, 17β-estradiol (E2), based on previously determined behavioral or teratogenic phenotypes. Functional analysis of differentially expressed genes revealed distinct expression profiles at 24 hours post fertilization for 0.1 versus 80 μM BPA and 0.1 versus 15 μM E2 exposure, identification of prothrombin activation as a top canonical pathway impacted by both 0.1 μM BPA and 0.1 μM E2 exposure, and suppressed expression of several genes involved in nervous system development and function following 0.1 μM BPAexposure.
PMCID: PMC3690774  PMID: 23557687
bisphenol A; 17β-estradiol; microarray; zebrafish; prothrombin; CREB
16.  IL-6-STAT3 signaling mediates aortic dissections induced by angiotensin II via the Th17 lymphocyte-IL17 axis in C57BL/6 Mice 
Arteriosclerosis, thrombosis, and vascular biology  2013;33(7):10.1161/ATVBAHA.112.301049.
Dysregulated angiotensin II (Ang II) signaling induces local vascular interleukin-6 (IL-6) secretion, producing leukocyte infiltration and life-threatening aortic dissections. Precise mechanism(s) by which IL-6 signaling induces leukocyte recruitment remain(s) unknown. T-helper 17lymphocytes (Th17) have been implicated in vascular pathology, but their role in the development of aortic dissections is poorly understood. Here, we tested the relationship of IL-6-STAT3 signaling with Th17-induced inflammation in the formation of Ang II-induced dissections in C57BL/6 mice.
Methods and Results
Ang II infusion induced aortic dissections and CD4+-interleukin 17A (IL-17A)-expressing, Th17 cell accumulation in C57BL/6 mice. A blunted local Th17 activation, macrophage recruitment, and reduced incidence of aortic dissections were seen in IL-6−/− mice. To determine pathological roles of Th17 lymphocytes, we treated Ang II infused mice with IL-17A neutralizing antibody (IL17A NAb), or infused Ang II in genetically deficientIL-17A mice, and found decreased aortic chemokine MCP-1 production and macrophage recruitment, leading to a reduction in aortic dissections. This effect was independent of blood pressure in IL17ANAb experiment. Application of a cell-permeable STAT3 inhibitor to downregulate the IL-6 pathway decreased aortic dilation and Th17 cell recruitment. We also observed increased aortic Th17 infiltration and IL-17 mRNA expression in patients with thoracic aortic dissections. Lastly, we found that Ang II mediated aortic dissections occurred independent of blood pressure changes.
Our results indicate that the IL-6-STAT3 signaling pathway converges on Th17 recruitment and IL-17A signaling upstream of macrophage recruitment, mediating aortic dissections.
PMCID: PMC3818154  PMID: 23685554
Angiotensin II; Aortic dissection; IL-6; Th17; Vascular inflammation
17.  Quasi-Immiscible Spreading of Aqueous Surfactant Solutions on Entangled Aqueous Polymer Solution Subphases 
ACS applied materials & interfaces  2013;5(12):5542-5549.
Motivated by the possibility of enhancing aerosol drug delivery to mucus-obstructed lungs, the spreading of a drop of aqueous surfactant solution on a physically entangled aqueous poly(acrylamide) solution subphase that mimics lung airway surface liquid was investigated. Sodium dodecyl sulfate was used as the surfactant. To visualize spreading of the drop and mimic the inclusion of a drug substance, fluorescein, a hydrophilic and non-surface active dye, was added to the surfactant solution. The spreading progresses through a series of events. Marangoni stresses initiate the convective spreading of the drop. Simultaneously, surfactant escapes across the drop’s contact line within a second of deposition and causes a change in subphase surface tension outside the drop on the order of 1 mN/m. Convective spreading of the drop ends within 2–3 seconds of drop deposition, when a new interfacial tension balance is achieved. Surfactant escape depletes the drop of surfactant and the residual drop takes the form of a static lens of non-zero contact angle. On longer time scales, the surfactant dissolves into the subphase. The lens formed by the water in the deposited drop persists for as long as 3 minutes after the convective spreading process ends due to the long diffusional timescales associated with the underlying entangled polymer solution. The persistence of the lens suggests that the drop phase behaves as if it were immiscible with the subphase during this time period. Whereas surfactant escapes the spreading drop and advances on the subphase/vapor interface, hydrophilic dye molecules in the drop do not escape, but remain with the drop throughout the convective spreading. The quasi-immiscible nature of the spreading event suggests that the chemical properties of the surfactant and subphase are much less important than their physical properties, consistent with prior qualitative studies of spreading of different types of surfactants on entangled polymer subphases: the selection of surfactant for pulmonary delivery applications may be limited only by physical and toxicological considerations. Further, the escape of surfactant from individual drops may provide an additional spreading mechanism in the lung as hydrodynamic and/or surface pressure repulsions may drive individual droplets apart after deposition.
PMCID: PMC3959907  PMID: 23705869
Marangoni flow; surfactant spreading; surfactant transport; pulmonary drug delivery
18.  Pathogenic Influenza Viruses and Coronaviruses Utilize Similar and Contrasting Approaches To Control Interferon-Stimulated Gene Responses 
mBio  2014;5(3):e01174-14.
The broad range and diversity of interferon-stimulated genes (ISGs) function to induce an antiviral state within the host, impeding viral pathogenesis. While successful respiratory viruses overcome individual ISG effectors, analysis of the global ISG response and subsequent viral antagonism has yet to be examined. Employing models of the human airway, transcriptomics and proteomics datasets were used to compare ISG response patterns following highly pathogenic H5N1 avian influenza (HPAI) A virus, 2009 pandemic H1N1, severe acute respiratory syndrome coronavirus (SARS-CoV), and Middle East respiratory syndrome CoV (MERS-CoV) infection. The results illustrated distinct approaches utilized by each virus to antagonize the global ISG response. In addition, the data revealed that highly virulent HPAI virus and MERS-CoV induce repressive histone modifications, which downregulate expression of ISG subsets. Notably, influenza A virus NS1 appears to play a central role in this histone-mediated downregulation in highly pathogenic influenza strains. Together, the work demonstrates the existence of unique and common viral strategies for controlling the global ISG response and provides a novel avenue for viral antagonism via altered histone modifications.
This work combines systems biology and experimental validation to identify and confirm strategies used by viruses to control the immune response. Using a novel screening approach, specific comparison between highly pathogenic influenza viruses and coronaviruses revealed similarities and differences in strategies to control the interferon and innate immune response. These findings were subsequently confirmed and explored, revealing both a common pathway of antagonism via type I interferon (IFN) delay as well as a novel avenue for control by altered histone modification. Together, the data highlight how comparative systems biology analysis can be combined with experimental validation to derive novel insights into viral pathogenesis.
PMCID: PMC4030454  PMID: 24846384
19.  Surface functionalities of gold nanoparticles impact embryonic gene expression responses 
Nanotoxicology  2012;7:192-201.
Incorporation of gold nanoparticles (AuNPs) into consumer products is increasing; however, there is a gap in available toxicological data to determine the safety of AuNPs. In this study, we utilised the embryonic zebrafish to investigate how surface functionalisation and charge influence molecular responses. Precisely engineered AuNPs with 1.5 nm cores were synthesised and functionalized with three ligands: 2-mercaptoethanesulfonic acid (MES), N,N,N-trimethylammoniumethanethiol (TMAT), or 2-(2-(2-mercaptoethoxy)ethoxy)ethanol. Developmental assessments revealed differential biological responses when embryos were exposed to the functionalised AuNPs at the same concentration. Using inductively coupled plasma–mass spectrometry, AuNP uptake was confirmed in exposed embryos. Following exposure to MES- and TMAT-AuNPs from 6 to 24 or 6 to 48 h post fertilisation, pathways involved in inflammation and immune response were perturbed. Additionally, transport mechanisms were misregulated after exposure to TMAT and MES-AuNPs, demonstrating that surface functionalisation influences many molecular pathways.
PMCID: PMC3399027  PMID: 22263968
Gold nanoparticles; toxicity; zebrafish; nanoparticle–biological interactions
20.  Diet-Induced Obesity Reprograms the Inflammatory Response of the Murine Lung to Inhaled Endotoxin 
Toxicology and applied pharmacology  2013;267(2):137-148.
The co-occurrence of environmental factors is common in complex human diseases and, as such, understanding the molecular responses involved is essential to determine risk and susceptibility to disease. We have investigated the key biological pathways that define susceptibility for pulmonary infection during obesity in diet-induced obese (DIO) and regular weight (RW) C57BL/6 mice exposed to inhaled lipopolysaccharide (LPS). LPS induced a strong inflammatory response in all mice as indicated by elevated cell counts of macrophages and neutrophils and levels of proinflammatory cytokines (MDC, MIP-1γ, IL-12, RANTES) in the bronchoalveolar lavage fluid. Additionally, DIO mice exhibited 50% greater macrophage cell counts, but decreased levels of the cytokines, IL-6, TARC, TNF-α, and VEGF relative to RW mice. Microarray analysis of lung tissue showed over half of the LPS-induced expression in DIO mice consisted of genes unique for obese mice, suggesting that obesity reprograms how the lung responds to subsequent insult. In particular, we found that obese animals exposed to LPS have gene signatures showing increased inflammatory and oxidative stress response and decreased antioxidant capacity compared to RW. Because signaling pathways for these responses can be common to various sources of environmentally induced lung damage, we further identified biomarkers that are indicative of specific toxicant exposure by comparing gene signatures after LPS exposure to those from a parallel study with cigarette smoke. These data show obesity may increase sensitivity to further insult and that co-occurrence of environmental stressors result in complex biosignatures that are not predicted from analysis of individual exposures.
PMCID: PMC3570597  PMID: 23306164
lipopolysaccharide; LPS; obesity; lung; inflammation; genomics 1
21.  Application of a Fuzzy Neural Network Model in Predicting Polycyclic Aromatic Hydrocarbon- Mediated Perturbations of the Cyp1b1 Transcriptional Regulatory Network in Mouse Skin 
Toxicology and applied pharmacology  2012;267(2):192-199.
Polycyclic aromatic hydrocarbons (PAHs) are present in the environment as complex mixtures with components that have diverse carcinogenic potencies and mostly unknown interactive effects. Non-additive PAH interactions have been observed in regulation of cytochrome P450 (CYP) gene expression in the CYP1 family. To better understand and predict biological effects of complex mixtures, such as environmental PAHs, an 11 gene input-1 gene output fuzzy neural network (FNN) was developed for predicting PAH-mediated perturbations of dermal Cyp1b1 transcription in mice. Input values were generalized using fuzzy logic into low, medium, and high fuzzy subsets, and sorted using k-means clustering to create Mamdani logic functions for predicting Cyp1b1 mRNA expression. Model testing was performed with data from microarray analysis of skin samples from FVB/N mice treated with toluene (vehicle control), dibenzo[def,p]chrysene (DBC), benzo[a]pyrene (BaP), or 1 of 3 combinations of diesel particulate extract (DPE), coal tar extract (CTE) and cigarette smoke condensate (CSC) using leave one out cross-validation. Predictions were within 1 log2 fold change unit of microarray data, with the exception of the DBC treatment group, where the unexpected down-regulation of Cyp1b1 expression was predicted but did not reach statistical significance on the microarrays. Adding CTE to DPE was predicted to increase Cyp1b1 expression, whereas adding CSC to CTE and DPE was predicted to have no effect, in agreement with microarray results. The aryl hydrocarbon receptor repressor (Ahrr) was determined to be the most significant input variable for model predictions using back-propagation and normalization of FNN weights.
PMCID: PMC3626406  PMID: 23274566
PAHs; modeling; mixtures; Cyp1b1; skin Ahrr
22.  IL‐6 Regulates Extracellular Matrix Remodeling Associated With Aortic Dilation in a Fibrillin‐1 Hypomorphic mgR/mgR Mouse Model of Severe Marfan Syndrome 
Development of thoracic aortic aneurysms is the most significant clinical phenotype in patients with Marfan syndrome. An inflammatory response has been described in advanced stages of the disease. Because the hallmark of vascular inflammation is local interleukin‐6 (IL‐6) secretion, we explored the role of this proinflammatory cytokine in the formation of aortic aneurysms and rupture in hypomorphic fibrillin‐deficient mice (mgR/mgR).
Methods and Results
MgR/mgR mice developed ascending aortic aneurysms with significant dilation of the ascending aorta by 12 weeks (2.7±0.1 and 1.3±0.1 for mgR/mgR versus wild‐type mice, respectively; P<0.001). IL‐6 signaling was increased in mgR/mgR aortas measured by increases in IL‐6 and SOCS3 mRNA transcripts (P<0.05) and in cytokine secretion of IL‐6, MCP‐1, and GM‐CSF (P<0.05). To investigate the role of IL‐6 signaling, we generated mgR homozygous mice with IL‐6 deficiency (DKO). The extracellular matrix of mgR/mgR mice showed significant disruption of elastin and the presence of dysregulated collagen deposition in the medial‐adventitial border by second harmonic generation multiphoton autofluorescence microscopy. DKO mice exhibited less elastin and collagen degeneration than mgR/mgR mice, which was associated with decreased activity of matrix metalloproteinase‐9 and had significantly reduced aortic dilation (1.0±0.1 versus 1.6±0.2 mm change from baseline, DKO versus mgR/mgR, P<0.05) that did not affect rupture and survival.
Activation of IL‐6‐STAT3 signaling contributes to aneurysmal dilation in mgR/mgR mice through increased MMP‐9 activity, aggravating extracellular matrix degradation.
PMCID: PMC3959679  PMID: 24449804
extracellular matrix; interleukin‐6; Marfan syndrome; matrix metalloproteinases; mgR; thoracic aortic aneurysms and dissections; vascular inflammation
23.  Early life stage trimethyltin exposure induces ADP-ribosylation factor expression and perturbs the vascular system in zebrafish 
Toxicology  2012;302(2-3):129-139.
Trimethyltin chloride (TMT) is an organotin contaminant, widely detected in aqueous environments, posing potential human and environmental risks. In this study, we utilized the zebrafish model to investigate the impact of transient TMT exposure on developmental progression, angiogenesis, and cardiovascular development. Embryos were waterborne exposed to a wide TMT concentration range from 8 to 96 hours post fertilization (hpf). The TMT concentration that led to mortality in 50% of the embryos (LC50) at 96 hpf was 8.2 μM; malformations in 50% of the embryos (EC50) was 2.8 μM. The predominant response observed in surviving embryos was pericardial edema. Additionally, using the Tg (fli1a: EGFP) y1 transgenic zebrafish line to non-invasively monitor vascular development, TMT exposure led to distinct disarrangements in the vascular system. The most susceptible developmental stage to TMT exposure was between 48–72 hpf. High density whole genome microarrays were used to identify the early transcriptional changes following TMT exposure from 48 to 60 hpf or 72 hpf. In total, 459 transcripts were differentially expressed at least 2-fold (P < 0.05) by TMT compared to control. Using Ingenuity Pathway Analysis (IPA) tools, it was revealed that the transcripts misregulated by TMT exposure were clustered in numerous categories including metabolic and cardiovascular disease, cellular function, cell death, molecular transport, and physiological development. In situ localization of highly elevated transcripts revealed intense staining of ADP-ribosylation factors arf3 and arf5 in the head, trunk, and tail regions. When arf5 expression was blocked by morpholinos, the zebrafish did not display the prototypical TMT-induced vascular deficits, indicating that the induction of arf5 was necessary for TMT-induced vascular toxicity.
PMCID: PMC3511642  PMID: 23000284
zebrafish; trimethyltin chloride; vascular; ADP-ribosylation factors (arf); gene expression
24.  Multifaceted Mechanisms of HIV Inhibition and Resistance to CCR5 Inhibitors PSC-RANTES and Maraviroc 
Small-molecule CCR5 antagonists, such as maraviroc (MVC), likely block HIV-1 through an allosteric, noncompetitive inhibition mechanism, whereas inhibition by agonists such as PSC-RANTES is less defined and may involve receptor removal by cell surface downregulation, competitive inhibition by occluding the HIV-1 envelope binding, and/or allosteric effects by altering CCR5 conformation. We explored the inhibitory mechanisms of maraviroc and PSC-RANTES by employing pairs of virus clones with differential sensitivities to these inhibitors. Intrinsic PSC-RANTES-resistant virus (YA versus RT) or those selected in PSC-RANTES treated macaques (M584 versus P3-4) only displayed resistance in multiple-cycle assays or with a CCR5 mutant that cannot be downregulated. In single-cycle assays, these HIV-1 clones displayed equal sensitivity to PSC-RANTES inhibition, suggesting effective receptor downregulation. Prolonged PSC-RANTES exposure resulted in desensitization of the receptor to internalization such that increasing virus concentration (substrate) could saturate the receptors and overcome PSC-RANTES inhibition. In contrast, resistance to MVC was observed with the MVC-resistant HIV-1 (R3 versus S2) in both multiple- and single-cycle assays and with altered virus concentrations, which is indicative of allosteric inhibition. MVC could also mediate inhibition and possibly resistance through competitive mechanisms.
PMCID: PMC3716150  PMID: 23529732
25.  Polycyclic aromatic hydrocarbons as skin carcinogens: Comparison of benzo[a]pyrene, dibenzo[def,p]chrysene and three environmental mixtures in the FVB/N mouse 
Toxicology and applied pharmacology  2012;264(3):377-386.
The polycyclic aromatic hydrocarbon (PAH), benzo[a]pyrene (BaP), was compared to dibenzo[def,p]chrysene (DBC) and combinations of three environmental PAH mixtures (coal tar, diesel particulate and cigarette smoke condensate) using a two stage, FVB/N mouse skin tumor model. DBC (4 nmol) was most potent, reaching 100% tumor incidence with a shorter latency to tumor formation, less than 20 weeks of 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion compared to all other treatments. Multiplicity was 4 times greater than BaP (400 nmol). Both PAHs produced primarily papillomas followed by squamous cell carcinoma and carcinoma in situ. Diesel particulate extract (1 mg SRM 1650b; mix 1) did not differ from toluene controls and failed to elicit a carcinogenic response. Addition of coal tar extract (1 mg SRM 1597a; mix 2) produced a response similar to BaP. Further addition of 2 mg of cigarette smoke condensate (mix 3) did not alter the response with mix 2. PAH-DNA adducts measured in epidermis 12 h post initiation and analyzed by 32P post- labeling, did not correlate with tumor incidence. PAH- dependent alteration in transcriptome of skin 12 h post initiation was assessed by microarray. Principal component analysis (sum of all treatments) of the 922 significantly altered genes (p<0.05), showed DBC and BaP to cluster distinct from PAH mixtures and each other. BaP and mixtures up-regulated phase 1 and 2 metabolizing enzymes while DBC did not. The carcinogenicity with DBC and two of the mixtures was much greater than would be predicted based on published Relative Potency Factors (RPFs).
PMCID: PMC3483092  PMID: 22935520
PAHs; Cyp1a1; Cyp1b1; adducts; relative potency factor; skin1

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