Different genes interact with particulate matter and tobacco smoke exposure in affecting lung function decline in the general population

Background

Oxidative stress related genes modify the effects of ambient air pollution or tobacco smoking on lung function decline. The impact of interactions might be substantial, but previous studies mostly focused on main effects of single genes.

Objectives

We studied the interaction of both exposures with a broad set of oxidative-stress related candidate genes and pathways on lung function decline and contrasted interactions between exposures.

Methods

For 12679 single nucleotide polymorphisms (SNPs), change in forced expiratory volume in one second (FEV₁), FEV₁ over forced vital capacity (FEV₁/FVC), and mean forced expiratory flow between 25 and 75% of the FVC (FEF_25-75) was regressed on interval exposure to particulate matter <10 µm in diameter (PM10) or packyears smoked (a), additive SNP effects (b), and interaction terms between (a) and (b) in 669 adults with GWAS data. Interaction p-values for 152 genes and 14 pathways were calculated by the adaptive rank truncation product (ARTP) method, and compared between exposures. Interaction effect sizes were contrasted for the strongest SNPs of nominally significant genes (p_interaction<0.05). Replication was attempted for SNPs with MAF>10% in 3320 SAPALDIA participants without GWAS.

Results

On the SNP-level, rs2035268 in gene SNCA accelerated FEV₁/FVC decline by 3.8% (p_interaction = 2.5×10⁻⁶), and rs12190800 in PARK2 attenuated FEV1 decline by 95.1 ml p_interaction = 9.7×10⁻⁸) over 11 years, while interacting with PM10. Genes and pathways nominally interacting with PM10 and packyears exposure differed substantially. Gene CRISP2 presented a significant interaction with PM10 (p_interaction = 3.0×10⁻⁴) on FEV₁/FVC decline. Pathway interactions were weak. Replications for the strongest SNPs in PARK2 and CRISP2 were not successful.

Conclusions

Consistent with a stratified response to increasing oxidative stress, different genes and pathways potentially mediate PM10 and tobacco smoke effects on lung function decline. Ignoring environmental exposures would miss these patterns, but achieving sufficient sample size and comparability across study samples is challenging.     

Herbal medicine use in the districts of Nakapiripirit, Pallisa, Kanungu, and Mukono in Uganda

ABSTRACT: BACKGROUND: Traditional medicine (TM) occupies a special place in the management of diseases in Uganda. Not with standing the many people relying on TM, indigenous knowledge (IK) related to TM is getting steadily eroded. To slow down this loss it is necessary to document and conserve as much of the knowledge as possible. This study was conducted to document the IK relevant to traditional medicine in the districts of Mukono, Nakapiripirit, Kanungu and Pallisa, in Uganda. METHODS: An ethnobotanical survey was conducted between October 2008 and February 2009 using techniques of key informant interviews and household interviews. RESULTS: The common diseases and conditions in the four districts include malaria, cough, headache, diarrhea, abdominal pain, flu, backache and eye diseases. Respondents stated that when they fall sick they self medicate using plant medicines or consult western-trained medicine practitioners. Self medication using herbal medicines was reported mostly by respondents of Nakapiripirit and Mukono. Respondents have knowledge to treat 78 ailments using herbal medicines. 44 species, mentioned by three or more respondents have been prioritized. The most frequently used part in herbal medicines is the leaf, followed by the stem and root. People sometime use animal parts, soil, salt and water from a grass roof, in traditional medicines. Herbal medicines are stored for short periods of time in bottles. The knowledge to treat ailments is acquired from parents and grandparents. Respondents' age and tribe appears to have a significant influence on knowledge of herbal medicine, while gender does not. CONCLUSION: This survey has indicated that IK associated with TM stills exists and that TM is still important in Uganda because many people use it as a first line of health care when they fall sick. Age and tribe influence the level of IK associated with herbal medicine, but gender does not.     

Ca2+ homeostasis regulates Xenopus oocyte maturation

In contrast to the well-defined role of Ca2+ signals during mitosis, the contribution of Ca2+ signaling to meiosis progression is controversial, despite several decades of investigating the role of Ca2+ and its effectors in vertebrate oocyte maturation. We have previously shown that during Xenopus oocyte maturation, Ca2+ signals are dispensable for entry into meiosis and for germinal vesicle breakdown. However, normal Ca2+ homeostasis is essential for completion of meiosis I and extrusion of the first polar body. In this study, we test the contribution of several downstream effectors in mediating the Ca2+ effects during oocyte maturation. We show that calmodulin and calcium-calmodulin-dependent protein kinase II (CAMK2) are not critical downstream Ca2+ effectors during meiotic maturation. In contrast, accumulation of Aurora kinase A (AURKA) protein is disrupted in cells deprived of Ca2+ signals. Since AURKA is required for bipolar spindle formation, failure to accumulate AURKA may contribute to the defective spindle phenotype following Ca2+ deprivation. These findings argue that Ca2+ homeostasis is important in establishing the oocyte's competence to undergo maturation in preparation for fertilization and embryonic development.     

Evaluation of the antiulcerogenic activity of violacein and its modulation by the inclusion complexation with beta-cyclodextrin

The effects of beta-cyclodextrin (betaCD) inclusion complexation on the ability of violacein to prevent gastric ulceration in mice were studied. Violacein-betaCD inclusion complexes were prepared in 1:1 and 1:2 molar ratios and analysed by differential scanning calorimetry and powder X-ray diffractometry. Violacein previously administered orally at 10 mg/kg significantly reduced indomethacin-induced gastric lesions, as well as 100 mg/kg of cimetidine (positive control). However, betaCD complexation in both molar ratios significantly potentiated the protective action of violacein. In the HCl--ethanol-induced gastric ulcer model, violacein and the 1:2 inclusion complex (10 mg/kg, p.o.) inhibited gastric damage by almost 85%, whereas a 63% reduction was observed for the positive control, lansoprazole, at 30 mg/kg. In contrast, treatment with the 1:1 inclusion complex resulted in almost total disappearance of the antiulcer activity in this model. No significant changes in stress-induced gastric injury were found. In addition, the 1:2 inclusion complex improved the antilipoperoxidant activity of violacein in rat liver cells exposed to t-butyl hydroperoxide, whereas the 1:1 complex was less active than violacein. In summary, the 1:2 betaCD inclusion complex has gastroprotective properties similar to or higher than that of violacein. An increase in mucosal defensive mechanisms and protection against peroxidative damage might be involved.     

Relationship between phosphatase activity and cytotoxic effect of two protein phosphatase inhibitors, okadaic acid and pervanadate, on human myeloid leukemia cell line

Protein phosphatases are signalling molecules that regulate a variety of fundamental cellular processes including cell growth, metabolism and apoptosis. The aim of this work was to correlate the cytotoxicity of pervanadate and okadaic acid on HL60 cells and their effect on the phosphatase obtained from these cells. The cytotoxicity of these protein phosphatase inhibitors was evaluated on HL60 cells using phosphatase activity, protein quantification and MTT reduction as indices. The major phosphatase presents in the cellular extract showed high activity (80%) and affinity (Km = 0.08 mM) to tyrosine phosphate in relation to p-nitrophenyl phosphate (pNPP)-(Km = 0.51 mM). Total phosphatase (pNPP) was inhibited in the presence of 10 mM vanadate (98%), 200 microM pervanadate (95%) and 100 microM p-chloromercuribenzoate (80%) but okadaic acid caused a slight increase in enzyme activity (25%). When the HL60 cells were treated with the phosphatase inhibitors (pervanadate and okadaic acid) for 24hours, only 20% residual activity was observed in presence of 200 microM pervanadate, whereas in the presence of okadaic acid this inhibitory effect was not observed. However, in respect to mitochondrial function, cell viability decreased about 80% in the presence of 100 nM okadaic acid. The total protein content was decreased 25% when the cells were treated with 100 nM okadaic acid in combination with 200 microM pervanadate. Our results suggest that both phosphatase inhibitors presented different mechanisms of action on HL60 cells. However, their effect on the cell redox status have to be considered.     

Sensitized photooxygenation and peroxidase-catalyzed inactivation of xanthine oxidase--evidence of cysteine damage by singlet oxygen

Xanthine oxidase (XO) has been investigated for its decreased activity in several cancerous tissues and constitutive generation of reactive oxygen species (ROS) in vivo seems to contribute significantly to its inactivation. Singlet oxygen (1O2) production has been suggested to be relevant when considering folic acid metabolism by cancer cells. Thus, the susceptibility of XO to inactivation by 1O2 generated either by the bioenergized systems folic acid/peroxidase/GSH/Mn2+/O2 and malonaldehyde/peroxidase/Mn2+/O2 or by methylene blue (MB) or eosin-sensitized photooxygenation was studied. Our results showed that other ROS were also responsible for XO inactivation when MB was used. In contrast, eosin produced almost exclusively 1O2. Kinetic studies of XO oxidation in the malonaldehyde/peroxidase system showed that histidine (His) is a competitive inhibitor with respect to XO. A similar result was observed in the eosin-photosensitized process, suggesting the involvement of 1O2 in both processes. In addition, an efficient quenching of XO oxidation by guanosine in the folic acid/peroxidase system was observed. Amino acid analysis revealed that cysteine (Cys) is more affected than other XO amino acids also prone to oxidation such as tyrosine (Tyr), methionine (Met) and His. These results indicate that 1O2 may cause oxidative damage to the Cys residues of XO, with loss of enzyme activity. Alteration of the flavin prosthetic site is hypothesized.     

Store-operated calcium entry inactivates at the germinal vesicle breakdown stage of Xenopus meiosis

Store-operated calcium entry (SOCE) is the predominant Ca(2+) influx pathway in non-excitable cells and is activated in response to depletion of intracellular Ca(2+) stores. We have studied SOCE regulation during Xenopus oocyte meiosis. SOCE can be measured readily in stage VI Xenopus oocytes arrested at the G(2)-M transition of the cell cycle, either by Ca(2+) imaging or by recording the SOCE current. However, following meiotic maturation, SOCE can no longer be activated by store depletion. We have characterized the time course of SOCE inactivation during oocyte maturation, and show that SOCE inactivates almost completely, in a very short time period, at the germinal vesicle breakdown stage of meiosis. This acute inactivation offers an opportunity to better understand SOCE regulation.     

Endoplasmic Reticulum Stress-Induced Autophagy Provides Cytoprotection from Chemical Hypoxia and Oxidant Injury and Ameliorates Renal Ischemia-Reperfusion Injury

We examined whether endoplasmic reticulum (ER) stress-induced autophagy provides cytoprotection from renal tubular epithelial cell injury due to oxidants and chemical hypoxia in vitro, as well as from ischemia-reperfusion (IR) injury in vivo. We demonstrate that the ER stress inducer tunicamycin triggers an unfolded protein response, upregulates ER chaperone Grp78, and activates the autophagy pathway in renal tubular epithelial cells in culture. Inhibition of ER stress-induced autophagy accelerated caspase–3 activation and cell death suggesting a pro-survival role of ER stress-induced autophagy. Compared to wild-type cells, autophagy-deficient MEFs subjected to ER stress had enhanced caspase–3 activation and cell death, a finding that further supports the cytoprotective role of ER stress-induced autophagy. Induction of autophagy by ER stress markedly afforded cytoprotection from oxidants H₂O₂ and tert-Butyl hydroperoxide and from chemical hypoxia induced by antimycin A. In contrast, inhibition of ER stress-induced autophagy or autophagy-deficient cells markedly enhanced cell death in response to oxidant injury and chemical hypoxia. In mouse kidney, similarly to renal epithelial cells in culture, tunicamycin triggered ER stress, markedly upregulated Grp78, and activated autophagy without impairing the autophagic flux. In addition, ER stress-induced autophagy markedly ameliorated renal IR injury as evident from significant improvement in renal function and histology. Inhibition of autophagy by chloroquine markedly increased renal IR injury. These studies highlight beneficial impact of ER stress-induced autophagy in renal ischemia-reperfusion injury both in vitro and in vivo.     

Glutamine synthetase in the phloem plays a major role in controlling proline production

To inhibit expression specifically in the phloem, a 274-bp fragment of a cDNA (Gln1-5) encoding cytosolic glutamine synthetase (GS1) from tobacco was placed in the antisense orientation downstream of the cytosolic Cu/Zn superoxide dismutase promoter of Nicotiana plumbaginifolia. After Agrobacterium-mediated transformation, two transgenic N. tabacum lines exhibiting reduced levels of GS1 mRNA and GS activity in midribs, stems, and roots were obtained. Immunogold labeling experiments allowed us to verify that the GS protein content was markedly decreased in the phloem companion cells of transformed plants. Moreover, a general decrease in proline content in the transgenic plants in comparison with wild-type tobacco was observed when plants were forced to assimilate large amounts of ammonium. In contrast, no major changes in the concentration of amino acids used for nitrogen transport were apparent. A (15)NH(4)(+)-labeling kinetic over a 48-hr period confirmed that in leaves of transgenic plants, the decrease in proline production was directly related to glutamine availability. After 2 weeks of salt treatment, the transgenic plants had a pronounced stress phenotype, consisting of wilting and bleaching in the older leaves. We conclude that GS in the phloem plays a major role in regulating proline production consistent with the function of proline as a nitrogen source and as a key metabolite synthesized in response to water stress.