Endoplasmic Reticulum - Mitochondrial Interactions in House Dust Mite Induced Inflammation

Rationale: Airway epithelial cells (AECs) are critical regulators of inflammatory, immune and injury responses to allergens that contribute to asthma pathogenesis. The response of AECs to allergens requires an integrated-complex, extracellular receptors and intracellular organelle interaction to achieve secretion of pro-inflammatory cytokines and chemokines. Endoplasmic reticulum (ER) and mitochondria interactions have previously been shown to induce mitochondrial fission. Mitochondrial fission may be a key parameter allergen induced airway inflammation in asthma. However, ER-mitochondria interactions, mitochondrial fission, and subsequent production and secretion of cytokines and chemokines in response to House Dust Mite (HDM) are not well understood. Objective: Here we will assess the ability of HDM to induce ER-mitochondrial interactions and subsequent mitochondrial fission in human bronchiolar epithelial (HBE) cells. We will also investigate the impact on cytokine production downstream of mitochondrial fission in HBE cells treated with HDM. Methods: ER-mitochondrial interactions were quantified using confocal and epifluorescence microscopy. Cytokine/chemokine profiles were determined by enzyme linked immunosorbant assay (ELISA) using HBE cells treated with HDM. Measurements and Main Results: Using epifluorescence and confocal microscopy we show that ER-mitochondrial contacts are increased in response to HDM treatment, as well as HDM-induced mitochondrial fission increased in HBE cells. Inhibition of DRP1, a protein essential for mitochondrial fission, decreases HDM induced ER-mitochondrial interaction. In addition, HDM-induced pro-inflammatory cytokines were decreased in HBE cells where mitochondrial fission is inhibited. Conclusion: HDM induces ER-Mitochondrial interactions that promote mitochondrial fission and subsequent production of pro-inflammatory cytokines

Repressionen gegen Ägyptens Zivilgesellschaft: staatliche Gewalt, Verengung des öffentlichen Raums und außergesetzliche Verfolgung

"Seit dem Militärputsch im Juli 2013 zeichnet sich das ägyptische Regime unter anderem dadurch aus, dass die Grenzen dessen, was an politischen Aktivitäten zulässig ist, nicht klar definiert werden. Die graduelle Verengung des öffentlichen Raums durch immer neue Präsidialdekrete zeigt vielmehr, dass sich die roten Linien jederzeit verschieben können. Dazu kommt in immer stärkerem Maße ein Missbrauch der Staatsgewalt gegen Vertreterinnen und Vertreter der ägyptischen Zivilgesellschaft, etwa in Form von Folter und Zwangsverschleppungen. Menschenrechtsaktivisten werden hierbei zunehmend von Zeugen zu Opfern von Übergriffen. Im Visier der Staatssicherheit, einer politisierten Judikative und konkurrierender Ministerien können sie ihre Rolle als Watchdogs immer weniger ausfüllen. Deutschland sollte sich vor diesem Hintergrund gemeinsam mit seinen europäischen Partnern für die Wahrung bürgerlicher Grundrechte und rechtsstaatlicher Standards in Ägypten einsetzen und seine Unterstützung stärker auf den Bedarf ägyptischer Nichtregierungsorganisationen abstimmen." (Autorenreferat

Oxidation state governs structural transitions in peroxiredoxin II that correlate with cell cycle arrest and recovery

Inactivation of eukaryotic 2-Cys peroxiredoxins (Prxs) by hyperoxidation has been proposed to promote accumulation of hydrogen peroxide (H2O2) for redox-dependent signaling events. We examined the oxidation and oligomeric states of PrxI and -II in epithelial cells during mitogenic signaling and in response to fluxes of H2O2. During normal mitogenic signaling, hyperoxidation of PrxI and -II was not detected. In contrast, H2O2-dependent cell cycle arrest was correlated with hyperoxidation of PrxII, which resulted in quantitative recruitment of ∼66- and ∼140-kD PrxII complexes into large filamentous oligomers. Expression of cyclin D1 and cell proliferation did not resume until PrxII-SO2H was reduced and native PrxII complexes were regenerated. Ectopic expression of PrxI or -II increased Prx-SO2H levels in response to oxidant exposure and failed to protect cells from arrest. We propose a model in which Prxs function as peroxide dosimeters in subcellular processes that involve redox cycling, with hyperoxidation controlling structural transitions that alert cells of perturbations in peroxide homeostasis

Glycolysis promotes caspase-3 activation in lipid rafts in T cells.

Resting T cells undergo a rapid metabolic shift to glycolysis upon activation in the presence of interleukin (IL)-2, in contrast to oxidative mitochondrial respiration with IL-15. Paralleling these different metabolic states are striking differences in susceptibility to restimulation-induced cell death (RICD); glycolytic effector T cells are highly sensitive to RICD, whereas non-glycolytic T cells are resistant. It is unclear whether the metabolic state of a T cell is linked to its susceptibility to RICD. Our findings reveal that IL-2-driven glycolysis promotes caspase-3 activity and increases sensitivity to RICD. Neither caspase-7, caspase-8, nor caspase-9 activity is affected by these metabolic differences. Inhibition of glycolysis with 2-deoxyglucose reduces caspase-3 activity as well as sensitivity to RICD. By contrast, IL-15-driven oxidative phosphorylation actively inhibits caspase-3 activity through its glutathionylation. We further observe active caspase-3 in the lipid rafts of glycolytic but not non-glycolytic T cells, suggesting a proximity-induced model of self-activation. Finally, we observe that effector T cells during influenza infection manifest higher levels of active caspase-3 than naive T cells. Collectively, our findings demonstrate that glycolysis drives caspase-3 activity and susceptibility to cell death in effector T cells independently of upstream caspases. Linking metabolism, caspase-3 activity, and cell death provides an intrinsic mechanism for T cells to limit the duration of effector function

Obesity exacerbates influenza-induced respiratory disease via the arachidonic acid-p38 MAPK pathway

Obesity is a risk factor for severe influenza, and asthma exacerbations caused by respiratory viral infections. We investigated mechanisms that increase the severity of airway disease related to influenza in obesity using cells derived from obese and lean individuals, and in vitro and in vivo models. Primary human nasal epithelial cells (pHNECs) derived from obese compared with lean individuals developed increased inflammation and injury in response to influenza A virus (IAV). Obese mice infected with influenza developed increased airway inflammation, lung injury and elastance, but had a decreased interferon response, compared with lean mice. Lung arachidonic acid (AA) levels increased in obese mice infected with IAV; arachidonic acid increased inflammatory cytokines and injury markers in response to IAV in human bronchial epithelial (HBE) cells. Obesity in mice, and AA in HBE cells, increased activation of p38 MAPK signaling following IAV infection; inhibiting this pathway attenuated inflammation, injury and tissue elastance responses, and improved survival. In summary, obesity increases disease severity in response to influenza infection through activation of the p38 MAPK pathway in response to altered arachidonic acid signaling

Redox amplification of apoptosis by caspase-dependent cleavage of glutaredoxin 1 and S-glutathionylation of Fas

Reactive oxygen species (ROS) increase ligation of Fas (CD95), a receptor important for regulation of programmed cell death. Glutathionylation of reactive cysteines represents an oxidative modification that can be reversed by glutaredoxins (Grxs). The goal of this study was to determine whether Fas is redox regulated under physiological conditions. In this study, we demonstrate that stimulation with Fas ligand (FasL) induces S-glutathionylation of Fas at cysteine 294 independently of nicotinamide adenine dinucleotide phosphate reduced oxidase–induced ROS. Instead, Fas is S-glutathionylated after caspase-dependent degradation of Grx1, increasing subsequent caspase activation and apoptosis. Conversely, overexpression of Grx1 attenuates S-glutathionylation of Fas and partially protects against FasL-induced apoptosis. Redox-mediated Fas modification promotes its aggregation and recruitment into lipid rafts and enhances binding of FasL. As a result, death-inducing signaling complex formation is also increased, and subsequent activation of caspase-8 and -3 is augmented. These results define a novel redox-based mechanism to propagate Fas-dependent apoptosis

Attenuation of lung fibrosis in mice with a clinically relevant inhibitor of glutathione-S-transferase π

Idiopathic pulmonary fibrosis (IPF) is a debilitating lung disease characterized by excessive collagen production and fibrogenesis. Apoptosis in lung epithelial cells is critical in IPF pathogenesis, as heightened loss of these cells promotes fibroblast activation and remodeling. Changes in glutathione redox status have been reported in IPF patients. S-glutathionylation, the conjugation of glutathione to reactive cysteines, is catalyzed in part by glutathione-S-transferase π (GSTP). To date, no published information exists linking GSTP and IPF to our knowledge. We hypothesized that GSTP mediates lung fibrogenesis in part through FAS S-glutathionylation, a critical event in epithelial cell apoptosis. Our results demonstrate that GSTP immunoreactivity is increased in the lungs of IPF patients, notably within type II epithelial cells. The FAS-GSTP interaction was also increased in IPF lungs. Bleomycin- and AdTGFβ-induced increases in collagen content, α-SMA, FAS S-glutathionylation, and total protein S-glutathionylation were strongly attenuated in Gstp(–/–) mice. Oropharyngeal administration of the GSTP inhibitor, TLK117, at a time when fibrosis was already apparent, attenuated bleomycin- and AdTGFβ-induced remodeling, α-SMA, caspase activation, FAS S-glutathionylation, and total protein S-glutathionylation. GSTP is an important driver of protein S-glutathionylation and lung fibrosis, and GSTP inhibition via the airways may be a novel therapeutic strategy for the treatment of IPF

Growth enhancement and food conversion efficiency of transgenic fish Labeo rohita

Three family lines of fast growing transgenic rohu Labeo rohita (rohu) were generated by electroporated-sperm-mediated transfer of the vectors harboring CMV promoter or grass carp β-actin promoter fused to endogenous rohu GH (rGH) cDNA. The gene transfer efficiency was 25%. The transgenic rohu (family line 1) with CMV promoter showed a growth enhancement of four times normal size, whereas those (family lines 2 and 3) generated with β-actin promoter grew 4.5 and 5.8 times faster than their respective control siblings. Southern analysis confirmed the transgene extrachromosomal (Te) persistence until the 60th week in family 1. The individuals of family lines 2 and 3, however, showed integration (Ti), as well as persistence as extarchromosomal copies (Te) until the age of 30 weeks. Mosaicism of the transgene was shown at the levels of its presence and expression. The ectopic expression of rGH mRNA was confirmed by RT-PCR. Feeding experiments revealed that the transgenic rohu ate food at a lower rate but grew more efficiently than their control siblings