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1.  Functional Genomic Assessment of Phosgene-Induced Acute Lung Injury in Mice 
In this study, a genetically diverse panel of 43 mouse strains was exposed to phosgene and genome-wide association mapping performed using a high-density single nucleotide polymorphism (SNP) assembly. Transcriptomic analysis was also used to improve the genetic resolution in the identification of genetic determinants of phosgene-induced acute lung injury (ALI). We prioritized the identified genes based on whether the encoded protein was previously associated with lung injury or contained a nonsynonymous SNP within a functional domain. Candidates were selected that contained a promoter SNP that could alter a putative transcription factor binding site and had variable expression by transcriptomic analyses. The latter two criteria also required that ≥10% of mice carried the minor allele and that this allele could account for ≥10% of the phenotypic difference noted between the strains at the phenotypic extremes. This integrative, functional approach revealed 14 candidate genes that included Atp1a1, Alox5, Galnt11, Hrh1, Mbd4, Phactr2, Plxnd1, Ptprt, Reln, and Zfand4, which had significant SNP associations, and Itga9, Man1a2, Mapk14, and Vwf, which had suggestive SNP associations. Of the genes with significant SNP associations, Atp1a1, Alox5, Plxnd1, Ptprt, and Zfand4 could be associated with ALI in several ways. Using a competitive electrophoretic mobility shift analysis, Atp1a1 promoter (rs215053185) oligonucleotide containing the minor G allele formed a major distinct faster-migrating complex. In addition, a gene with a suggestive SNP association, Itga9, is linked to transforming growth factor β1 signaling, which previously has been associated with the susceptibility to ALI in mice.
PMCID: PMC3824050  PMID: 23590305
ARDS; countermeasures; genetics; sodium absorption; lipoxygenase
2.  Role of Hypoxia-Inducible Factor 1, α Subunit and cAMP-Response Element Binding Protein 1 in Synergistic Release of Interleukin 8 by Prostaglandin E2 and Nickel in Lung Fibroblasts 
Numerous epidemiological studies have linked exposure to particulate matter (PM) air pollution with acute respiratory infection and chronic respiratory and cardiovascular diseases. We have previously shown that soluble nickel (Ni), a common component of PM, alters the release of CXC chemokines from cultured human lung fibroblasts (HLF) in response to microbial stimuli via a pathway dependent on disrupted prostaglandin (PG)E2 signaling. The current study sought to identify the molecular events underlying Ni-induced alterations in PGE2 signaling and its effects on IL-8 production. PGE2 synergistically enhances Ni-induced IL-8 release from HLF in a concentration-dependent manner. The effects of PGE2 were mimicked by butaprost and PGE1-alcohol and inhibited with antagonists AH6809 and L-161,982, indicating PGE2 signals via PGE2 receptors 2 and 4. PGE2 and forskolin stimulated cAMP, but it was only in the presence of Ni-induced hypoxia-inducible factor 1, α subunit (HIF1A) that these agents stimulated IL-8 release. The Ni-induced HIF1A DNA binding was enhanced by PGE2 and mediated, in part, by activation of p38 MAPK. Negation of cAMP-response element binding protein 1 or HIF1A using short interfering RNA blocked the synergistic interactions between Ni and PGE2. The results of the current study provide novel information on the ability of atmospheric hypoxia-mimetic metals to disrupt the release of immune-modulating chemokines by HLF in response to PGE2. Moreover, in the presence of HIF1A, cAMP-mediated signaling pathways may be altered to exacerbate inflammatory-like processes in lung tissue, imparting a susceptibility of PM-exposed populations to adverse respiratory health effects.
PMCID: PMC3727881  PMID: 23526216
prostaglandin E2; HIF1A; nickel; IL-8; fibroblast
3.  Integrative Assessment of Chlorine-Induced Acute Lung Injury in Mice 
The genetic basis for the underlying individual susceptibility to chlorine-induced acute lung injury is unknown. To uncover the genetic basis and pathophysiological processes that could provide additional homeostatic capacities during lung injury, 40 inbred murine strains were exposed to chlorine, and haplotype association mapping was performed. The identified single-nucleotide polymorphism (SNP) associations were evaluated through transcriptomic and metabolomic profiling. Using ≥ 10% allelic frequency and ≥ 10% phenotype explained as threshold criteria, promoter SNPs that could eliminate putative transcriptional factor recognition sites in candidate genes were assessed by determining transcript levels through microarray and reverse real-time PCR during chlorine exposure. The mean survival time varied by approximately 5-fold among strains, and SNP associations were identified for 13 candidate genes on chromosomes 1, 4, 5, 9, and 15. Microarrays revealed several differentially enriched pathways, including protein transport (decreased more in the sensitive C57BLKS/J lung) and protein catabolic process (increased more in the resistant C57BL/10J lung). Lung metabolomic profiling revealed 95 of the 280 metabolites measured were altered by chlorine exposure, and included alanine, which decreased more in the C57BLKS/J than in the C57BL/10J strain, and glutamine, which increased more in the C57BL/10J than in the C57BLKS/J strain. Genetic associations from haplotype mapping were strengthened by an integrated assessment using transcriptomic and metabolomic profiling. The leading candidate genes associated with increased susceptibility to acute lung injury in mice included Klf4, Sema7a, Tns1, Aacs, and a gene that encodes an amino acid carrier, Slc38a4.
PMCID: PMC3423464  PMID: 22447970
ARDS; countermeasures; glutamine; genetics; metabolomics
4.  Integrative Metabolome and Transcriptome Profiling Reveals Discordant Energetic Stress between Mouse Strains with Differential Sensitivity to Acrolein-Induced Acute Lung Injury 
Molecular nutrition & food research  2011;55(9):1423-1434.
A respiratory irritant, acrolein is generated by overheating cooking oils or by domestic cooking using biomass fuels, and is in tobacco smoke, an occupational health hazard in the restaurant workplace. To better understand the metabolic role of the lung and to generate insights into the pathogenesis of acrolein-induced acute lung injury, SM/J (sensitive) and 129×1/SvJ (resistant) inbred mouse strains were exposed and the lung metabolome was integrated with the transcriptome profile. A total of 280 small molecules were identified and mean values (log 2 >0.58 or <−0.58, .p<0.05) were considered different for between-strain comparisons or within-strain responses to acrolein treatment. At baseline, 24 small molecules increased and 33 small molecules decreased in the SM/J mouse lung as compared to 129×1/SvJ mouse lung. Notable among the increased compounds was malonyl carnitine. Following acrolein exposure, several compounds indicative of glycolysis and branched chain amino acid metabolism increased similarly in both strains, whereas SM/J mice were less effective in generating metabolites related to fatty acid β-oxidation. These findings suggest management of energetic stress varies between these strains, and that the ability to evoke auxiliary energy generating pathways rapidly and effectively may be critical in enhancing survival during acute lung injury in mice.
PMCID: PMC3482455  PMID: 21823223
ARDS; Smoke Inhalation; Protein Folding; Mitochondrion; Beta-oxidation
5.  Haplotype Association Mapping of Acute Lung Injury in Mice Implicates Activin A Receptor, Type 1 
Rationale: Because acute lung injury is a sporadic disease produced by heterogeneous precipitating factors, previous genetic analyses are mainly limited to candidate gene case-control studies.
Objectives: To develop a genome-wide strategy in which single nucleotide polymorphism associations are assessed for functional consequences to survival during acute lung injury in mice.
Methods: To identify genes associated with acute lung injury, 40 inbred strains were exposed to acrolein and haplotype association mapping, microarray, and DNA-protein binding were assessed.
Measurements and Main Results: The mean survival time varied among mouse strains with polar strains differing approximately 2.5-fold. Associations were identified on chromosomes 1, 2, 4, 11, and 12. Seven genes (Acvr1, Cacnb4, Ccdc148, Galnt13, Rfwd2, Rpap2, and Tgfbr3) had single nucleotide polymorphism (SNP) associations within the gene. Because SNP associations may encompass “blocks” of associated variants, functional assessment was performed in 91 genes within ± 1 Mbp of each SNP association. Using 10% or greater allelic frequency and 10% or greater phenotype explained as threshold criteria, 16 genes were assessed by microarray and reverse real-time polymerase chain reaction. Microarray revealed several enriched pathways including transforming growth factor-β signaling. Transcripts for Acvr1, Arhgap15, Cacybp, Rfwd2, and Tgfbr3 differed between the strains with exposure and contained SNPs that could eliminate putative transcriptional factor recognition sites. Ccdc148, Fancl, and Tnn had sequence differences that could produce an amino acid substitution. Mycn and Mgat4a had a promoter SNP or 3′untranslated region SNPs, respectively. Several genes were related and encoded receptors (ACVR1, TGFBR3), transcription factors (MYCN, possibly CCDC148), and ubiquitin-proteasome (RFWD2, FANCL, CACYBP) proteins that can modulate cell signaling. An Acvr1 SNP eliminated a putative ELK1 binding site and diminished DNA–protein binding.
Conclusions: Assessment of genetic associations can be strengthened using a genetic/genomic approach. This approach identified several candidate genes, including Acvr1, associated with increased susceptibility to acute lung injury in mice.
PMCID: PMC3137140  PMID: 21297076
acute respiratory distress syndrome; smoke inhalation; carboxyl stress; transforming growth factor-&beta signaling; ubiquitination
6.  Endothelial Dysfunction and Claudin 5 Regulation during Acrolein-Induced Lung Injury 
An integral membrane protein, Claudin 5 (CLDN5), is a critical component of endothelial tight junctions that control pericellular permeability. Breaching of endothelial barriers is a key event in the development of pulmonary edema during acute lung injury (ALI). A major irritant in smoke, acrolein can induce ALI possibly by altering CLDN5 expression. This study sought to determine the cell signaling mechanism controlling endothelial CLDN5 expression during ALI. To assess susceptibility, 12 mouse strains were exposed to acrolein (10 ppm, 24 h), and survival monitored. Histology, lavage protein, and CLDN5 transcripts were measured in the lung of the most sensitive and resistant strains. CLDN5 transcripts and phosphorylation status of forkhead box O1 (FOXO1) and catenin (cadherin-associated protein) beta 1 (CTNNB1) proteins were determined in control and acrolein-treated human endothelial cells. Mean survival time (MST) varied more than 2-fold among strains with the susceptible (BALB/cByJ) and resistant (129X1/SvJ) strains (MST, 17.3 ± 1.9 h vs. 41.4 ± 5.1 h, respectively). Histological analysis revealed earlier perivascular enlargement in the BALB/cByJ than in 129X1/SvJ mouse lung. Lung CLDN5 transcript and protein increased more in the resistant strain than in the susceptible strain. In human endothelial cells, 30 nM acrolein increased CLDN5 transcripts and increased p-FOXO1 protein levels. The phosphatidylinositol 3-kinase inhibitor LY294002 diminished the acrolein-induced increased CLDN5 transcript. Acrolein (300 nM) decreased CLDN5 transcripts, which were accompanied by increased FOXO1 and CTNNB1. The phosphorylation status of these transcription factors was consistent with the observed CLDN5 alteration. Preservation of endothelial CLDN5 may be a novel clinical approach for ALI therapy.
PMCID: PMC3095921  PMID: 20525806
ARDS; perivascular edema; vascular permeability; smoke inhalation; carboxyl stress
Toxicology and applied pharmacology  2010;247(2):146-157.
Microbial stimuli and atmospheric particulate matter (PM) interact to amplify the release of inflammatory and immune-modulating cytokines. The basis of this interaction, however, is not known. Cultured human lung fibroblasts (HLF) were used to determine whether various protein kinase pathways were involved in the release of IL-6 following combined exposure to the PM-derived metal, Ni, and M. fermentans-derived macrophage-activating lipopeptide 2 (MALP-2), a toll-like receptor 2 agonist. Synergistic release of IL-6 by MALP-2 and NiSO4 was obvious after 8 h of co-stimulation and correlated with a late phase accumulation of IL-6 mRNA. Ni and MALP-2, alone or together, all lead to rapid and transient phosphorylations of ERK1/2 and JNK/SAPK of similar magnitude. p38 phosphorylation, however, was observed only after prolonged treatment of cells with both stimuli together. A constitutive level of PI3K-dependent Akt phosphorylation remained unchanged by Ni and/or MALP-2 exposure. IL-6 induced by Ni/MALP-2 co-exposure was partially dependent on activity of HIF-1α and COX-2 as shown by targeted knockdown using siRNA. IL-6 release in response to Ni/MALP-2 was partially sensitive to pharmacological inhibition of ERK1/2, p38, and PI3K signaling. The protein kinase inhibitors had minimal or no effects on Ni/MALP-2-induced accumulation of HIF-1α protein, however, COX-2 expression and, more markedly PGE2 production, were suppressed by LY294002, SB203580, and U0126. Thus, Ni/MALP-2 interactions involve multiple protein kinase pathways (ERK1/2, p38, and PI3K) that modulate events downstream from the early accumulation of HIF-1α to promote IL-6 gene expression directly or secondarily, through COX-2-derived autocrine products like PGE2.
PMCID: PMC2919161  PMID: 20600219
airborne particulate-derived metals; mitogen-activated protein kinase; p38; phosphoinositide 3-kinase; cyclooxygenase; hypoxia-inducible factor-1α; innate immunity; cytokines
8.  Functional Genomics of Chlorine-induced Acute Lung Injury in Mice 
Acute lung injury can be induced indirectly (e.g., sepsis) or directly (e.g., chlorine inhalation). Because treatment is still limited to supportive measures, mortality remains high (∼74,500 deaths/yr). In the past, accidental (railroad derailments) and intentional (Iraq terrorism) chlorine exposures have led to deaths and hospitalizations from acute lung injury. To better understand the molecular events controlling chlorine-induced acute lung injury, we have developed a functional genomics approach using inbred mice strains. Various mouse strains were exposed to chlorine (45 ppm × 24 h) and survival was monitored. The most divergent strains varied by more than threefold in mean survival time, supporting the likelihood of an underlying genetic basis of susceptibility. These divergent strains are excellent models for additional genetic analysis to identify critical candidate genes controlling chlorine-induced acute lung injury. Gene-targeted mice then could be used to test the functional significance of susceptibility candidate genes, which could be valuable in revealing novel insights into the biology of acute lung injury.
PMCID: PMC3136967  PMID: 20601635
pulmonary edema; vascular permeability; terrorism countermeasures; acute respiratory distress syndrome
9.  Nickel and the Microbial Toxin, MALP-2, Stimulate Proangiogenic Mediators from Human Lung Fibroblasts via a HIF-1α and COX-2–Mediated Pathway 
Toxicological Sciences  2008;107(1):227-237.
Hypoxia-inducible factor (HIF-1α) and cyclooxygenase-2 (COX-2) have been implicated in the regulation of inflammatory-like processes that lead to angiogenesis and fibrotic disorders. Here we demonstrate that in human lung fibroblasts (HLFs) treated with mixed exposures to chemical and microbial stimuli, HIF-1α stabilization plays a pivotal role in the induction of COX-2 mRNA and protein, driving the release of vascular endothelial growth factor (VEGF) and proangiogenic and profibrotic chemokines. Upon costimulation with Ni and the mycoplasma-derived lipopeptide macrophage-activating lipopeptide-2 (MALP-2), there was a synergistic induction of CXCL1 and CXCL5 mRNA and protein release from HLF, as well as an enhanced response in VEGF compared to either stimulus alone. Consistent with our previous findings that Ni and MALP-2 stimulates the induction of CXCL8 via a COX-2-mediated pathway, CXCL1, CXCL5, and VEGF release were also regulated by COX-2. Ni induced the stabilization of HIF-1α protein in HLF, which was further enhanced in the presence of MALP-2. Depletion of HIF-1α using siRNA blocked COX-2 induction by Ni and MALP-2 along with the release of VEGF, CXCL1, CXCL5, and CXCL8. Our results indicate that Ni and MALP-2 interact to promote an angiogenic profibrotic phenotype in HLF. Moreover, these findings reveal a potential role for HIF-1α in mediating chemical-induced alterations in cellular response to microbial stimuli, modulating pulmonary inflammation and its consequences such as fibrosis and angiogenesis.
PMCID: PMC2638645  PMID: 18832182
HIF-1α; COX-2; fibroblasts; inflammation; Ni; MALP-2
10.  Nickel Alterations of TLR2-Dependent Chemokine Profiles in Lung Fibroblasts Are Mediated by COX-2 
Particulate matter air pollution (PM) has been linked with chronic respiratory diseases. Real-life exposures are likely to involve a mixture of chemical and microbial stimuli, yet little attention has been paid to the potential interactions between PM components (e.g., Ni) and microbial agents on the development of inflammatory-like conditions in the lung. Using the Toll-like receptor (TLR)-2 agonist MALP-2 as a lipopeptide relevant to microbial colonization, we hypothesized that nickel sensitizes human lung fibroblasts (HLF) for microbial-driven chemokine release through modulation of TLR signaling pathways. NiSO4 (200 μM) synergistically enhanced CXCL8, yet antagonized CXCL10 mRNA expression and protein release from HLF in response to MALP-2. RT2-PCR pathway-focused array results indicated that NiSO4 exposure did not alter the expression of TLRs or their downstream signaling mediators, yet significantly increased the expression of cyclooxygenase 2 (COX-2). Moreover, when NiSO4 was given in combination with MALP-2, there was an amplified induction of COX-2 mRNA and protein along with its metabolic product, PGE2, in HLF. The COX-2 inhibitor, NS-398, attenuated NiSO4 and MALP-2–induced PGE2 and CXCL8 release and partially reversed the NiSO4-dependent inhibition of MALP-2–induced CXCL10 release from HLF. These data indicate that NiSO4 alters the pattern of TLR-2–dependent chemokine release from HLF via a COX-2–mediated pathway. The quantitative and qualitative effects of NiSO4 on microbial-driven chemokine release from HLF shed new light on how PM-derived metals can exacerbate respiratory diseases.
PMCID: PMC2335339  PMID: 18096868
COX-2; nickel; inflammation; chemokines; fibroblasts
11.  Sustained inhibition of rat myometrial gap junctions and contractions by lindane 
Gap junctions increase in size and abundance coincident with parturition, forming an intercellular communication network that permits the uterus to develop the forceful, coordinated contractions necessary for delivery of the fetus. Lindane, a pesticide used in the human and veterinary treatment of scabies and lice as well as in agricultural applications, inhibits uterine contractions in vitro, inhibits myometrial gap junctions, and has been associated with prolonged gestation length in rats. The aim of the present study was to investigate whether brief exposures to lindane would elicit sustained inhibition of rat uterine contractile activity and myometrial gap junction intercellular communication.
To examine effects on uterine contraction, longitudinal uterine strips isolated from late gestation (day 20) rats were exposed to lindane in muscle baths and monitored for changes in spontaneous phasic contractions during and after exposure to lindane. Lucifer yellow dye transfer between myometrial cells in culture was used to monitor gap junction intercellular communication.
During a 1-h exposure, 10 micro M and 100 micro M lindane decreased peak force and frequency of uterine contraction but 1 micro M lindane did not. After removal of the exposure buffer, contraction force remained significantly depressed in uterine strips exposed to 100 micro M lindane, returning to less than 50% basal levels 5 h after cessation of lindane exposure. In cultured myometrial myocytes, significant sustained inhibition of Lucifer yellow dye transfer was observed 24 h after lindane exposures as brief as 10 min and as low as 0.1 micro M lindane.
Brief in vitro exposures to lindane have long-term effects on myometrial functions that are necessary for parturition, inhibiting spontaneous phasic contractions in late gestation rat uterus and gap junction intercellular communication in myometrial cell cultures.
PMCID: PMC222921  PMID: 14567758

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