TNF and ROS Crosstalk in Inflammation.

peer reviewedTumor necrosis factor (TNF) is tremendously important for mammalian immunity and cellular homeostasis. The role of TNF as a master regulator in balancing cell survival, apoptosis and necroptosis has been extensively studied in various cell types and tissues. Although these findings have revealed much about the direct impact of TNF on the regulation of NF-κB and JNK, there is now rising interest in understanding the emerging function of TNF as a regulator of the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). In this review we summarize work aimed at defining the role of TNF in the control of ROS/RNS signaling that influences innate immune cells under both physiological and inflammatory conditions

Control of Chemokine-Guided Cell Migration by Ligand Sequestration

SummaryPrimordial germ cell (PGC) migration in zebrafish is directed by the chemokine SDF-1a that activates its receptor CXCR4b. Little is known about the molecular mechanisms controlling the distribution of this chemoattractant in vivo. We demonstrate that the activity of a second SDF-1/CXCL12 receptor, CXCR7, is crucial for proper migration of PGCs toward their targets. We show that CXCR7 functions primarily in the somatic environment rather than within the migrating cells. In CXCR7 knocked-down embryos, the PGCs exhibit a phenotype that signifies defects in SDF-1a gradient formation as the cells fail to polarize effectively and to migrate toward their targets. Indeed, somatic cells expressing CXCR7 show enhanced internalization of the chemokine suggesting that CXCR7 acts as a sink for SDF-1a, thus allowing the dynamic changes in the transcription of sdf-1a to be mirrored by similar dynamics at the protein level

Global trends in myopia management attitudes and strategies in clinical practice – 2019 Update

Purpose: A survey in 2015 identified a high level of eye care practitioner concern about myopia with a reported moderately high level of activity, but the vast majority still prescribed single vision interventions to young myopes. This research aimed to update these findings 4 years later. Methods: A self-administrated, internet-based questionnaire was distributed in eight languages, through professional bodies to eye care practitioners globally. The questions examined: awareness of increasing myopia prevalence, perceived efficacy of available strategies and adoption levels of such strategies, and reasons for not adopting specific strategies. Results: Of the 1336 respondents, concern was highest (9.0 ± 1.6; p < 0.001) in Asia and lowest (7.6 ± 2.2; p < 0.001) in Australasia. Practitioners from Asia also considered their clinical practice of myopia control to be the most active (7.7 ± 2.3; p < 0.001), the North American practitioners being the least active (6.3 ± 2.9; p < 0.001). Orthokeratology was perceived to be the most effective method of myopia control, followed by pharmaceutical approaches and approved myopia control soft contact lenses (p < 0.001). Although significant intra-regional differences existed, overall, most practitioners did not consider single-vision distance under-correction to be an effective strategy for attenuating myopia progression (79.6 %), but prescribed single vision spectacles or contact lenses as the primary mode of correction for myopic patients (63.6 ± 21.8 %). The main justifications for their reluctance to prescribe alternatives to single vision refractive corrections were increased cost (20.6 %) and inadequate information (17.6 %). Conclusions: While practitioner concern about myopia and the reported level of activity have increased over the last 4 years, the vast majority of eye care clinicians still prescribe single vision interventions to young myopes. With recent global consensus evidence-based guidelines having been published, it is hoped that this will inform the practice of myopia management in future

Molekulare und zelluläre Mechanismen, welche die Primordiale Keimzell-Migration im Zebrafisch kontrollieren.

Im Zebrafisch spezifizieren sich die primordialen Keimzellen schon im frühen Stadium der embryonalen Entwicklung und migrieren anschließend zur Region wo die Gonaden gebildet werden, wo sie sich schlussendlich zu Gameten (Eier oder Spermien) entwickeln. Das Chemokin SDF-1 wird von somatischen Mesoderm Zellen exprimiert und dient als Wegweiser für die migrierenden Keimzellen, die wiederum den korrespondierenden Rezeptor CXCR4b exprimieren.Hier beschreiben wir die Klonierung der Promoter-Region des Gens askopos, welche wir an ein Reporter-Gen und bestimmte RNA Elemente fusioniert haben, die wiederum zur spezifischen Stabilisierung und Translation der RNA in den Keimzellen führte. Wir benutzten dieses Konstrukt um einen transgenen Fisch zu erzeugen, welcher uns erlaubte, die Entwicklung der primordialen Keimzellen während den frühen embryonalen Entwicklungsphasen zu verfolgen. Diese Analyse offenbarte uns verschiedene Phasen der primordialen Keimzellentwicklung. Während der letzten Phase ändern die primordialen Keimzellen ihr Verhalten und beginnen zu migrieren. Erst ab dieser Phase können die Keimzellen auf das von somatischen Zellen exprimierte SDF-1a reagieren und geleitet werden. Zusätzlich detektierten wir eine Reduzierung des Proteins E-cadherin beim Eintritt in die letzte Phase der primoridalen Keimzellentwicklung. Nebenbei konnten wir auch zeigen, dass die letzte Phase von der Funktion des Dead end Proteins und von de novo Transkription abhängt.Nachdem die Keimzellen das migrieren erlernt haben, können sie sofort aktiv in Richtung SDF-1a migrieren. In dem Bestreben herauszufinden wie das Chemokin Signal von der Zelle in ausgerichtete Migration interpretiert wird, haben wir die Beobachtung gemacht, dass migrierende Keimzellen konstant hohe Kalzium Konzentrationen an der Front aufweisen. Manipulationen der Kalzium-Verteilung in der Zelle resultierten in schwerwiegenden Problemen der Zell-Polarisation und Migration. Solch manipulierte Keimzellen zeigten eine ungewöhnlich hohe Anzahl an Protrusion, was die Migrationsgeschwindigkeit so stark beeinflusste, dass viele Keimzellen in ektopischen Regionen im Embryo wieder gefunden wurden. Um die molekulare Kaskade zu ermitteln, die von Kalzium aktiviert wird, analysierten wir die Funktion von MLCK in dem Prozess der Keimzell-Migration. Wir entdeckten, dass MLCK in der Front von migrierenden primordialen Keimzellen lokalisiert und dass die Aktivität von MLCK wichtig ist für die kontrollierte Formation von Protrusion. In der Tat, bei der Expression von einer aktivierten und einer dominant negativen Form von MLCK, zeigten die Keimzellen Probleme bei der Polarisierung, der Protrusion-Formation und ein drastischer Anstieg der verbrachten Zeit in der tumbling -Phase wurde registriert. Ebenso konnten wir die Aktivierung von myosin hauptsächlich an der Front von migrierenden primordialen Keimzellen detektieren. Die erhöhte Kalziumkonzentration an der Front könnte schlussendlich wichtig sein, um die Aktivität von MLCK zu regulieren, welche andererseits die Kontraktion vom Acto-myosin Kortex auslöst, und damit die Formation von Protrusion an der Front der Zelle und beständige Migration ermöglicht

Helicobacter pylori Avoids the Critical Activation of NLRP3 Inflammasome-Mediated Production of Oncogenic Mature IL-1β in Human Immune Cells

Helicobacter pylori persistently colonizes the human stomach, and is associated with inflammation-induced gastric cancer. Bacterial crosstalk with the host immune system produces various inflammatory mediators and subsequent reactions in the host, but not bacterial clearance. Interleukin-1β (IL-1β) is implicated in gastric cancer development and certain gene polymorphisms play a role in this scenario. Mature IL-1β production depends on inflammasome activation, and the NLRP3 inflammasome is a major driver in H. pylori-infected mice, while recent studies demonstrated the down-regulation of NLRP3 expression in human immune cells, indicating a differential NLRP3 regulation in human vs. mice. In addition to the formation of mature IL-1β or IL-18, inflammasome activation induces pyroptotic death in cells. We demonstrate that H. pylori infection indeed upregulated the expression of pro-IL-1β in human immune cells, but secreted only very low amounts of mature IL-1β. However, application of exogenous control activators such as Nigericin or ATP to infected cells readily induced NLRP3 inflammasome formation and secretion of high amounts of mature IL-1β. This suggests that chronic H. pylori infection in humans manipulates inflammasome activation and pyroptosis for bacterial persistence. This inflammasome deregulation during H. pylori infection, however, is prone to external stimulation by microbial, environmental or host molecules of inflammasome activators for the production of high amounts of mature IL-1β and signaling-mediated gastric tumorigenesis in humans

Direct association of Bloom's syndrome gene product with the human mismatch repair protein MLH1

Bloom's syndrome (BS) is a rare genetic disorder characterised by genomic instability and cancer susceptibility. BLM, the gene mutated in BS, encodes a member of the RecQ family of DNA helicases. Here, we identify hMLH1, which is involved in mismatch repair (MMR) and recombination, as a protein that directly interacts with BLM both in vivo and in vitro, and that the two proteins co-localise to discrete nuclear foci. The interaction between BLM and hMLH1 appears to have been evolutionarily conserved, as Sgs1p, the Saccharomyces cerevisiae homologue of BLM, interacts with yeast Mlh1p. However, cell extracts derived from BS patients show no obvious defects in MMR compared to wild-type- and BLM-complemented BS cell extracts. We conclude that the hMLH1-BLM interaction is not essential for post-replicative MMR, but, more likely, is required for some aspect of genetic recombinatio

Direct association of Bloom’s syndrome gene product with the human mismatch repair protein MLH1

Bloom’s syndrome (BS) is a rare genetic disorder characterised by genomic instability and cancer susceptibility. BLM, the gene mutated in BS, encodes a member of the RecQ family of DNA helicases. Here, we identify hMLH1, which is involved in mismatch repair (MMR) and recombination, as a protein that directly interacts with BLM both in vivo and in vitro, and that the two proteins co-localise to discrete nuclear foci. The interaction between BLM and hMLH1 appears to have been evolutionarily conserved, as Sgs1p, the Saccharomyces cerevisiae homologue of BLM, interacts with yeast Mlh1p. However, cell extracts derived from BS patients show no obvious defects in MMR compared to wild-type- and BLM-complemented BS cell extracts. We conclude that the hMLH1–BLM interaction is not essential for post-replicative MMR, but, more likely, is required for some aspect of genetic recombination