Necroptosis blockade prevents lung injury in severe influenza.

Severe influenza A virus (IAV) infections can result in hyper-inflammation, lung injury and acute respiratory distress syndrome1-5 (ARDS), for which there are no effective pharmacological therapies. Necroptosis is an attractive entry point for therapeutic intervention in ARDS and related inflammatory conditions because it drives pathogenic lung inflammation and lethality during severe IAV infection6-8 and can potentially be targeted by receptor interacting protein kinase 3 (RIPK3) inhibitors. Here we show that a newly developed RIPK3 inhibitor, UH15-38, potently and selectively blocked IAV-triggered necroptosis in alveolar epithelial cells in vivo. UH15-38 ameliorated lung inflammation and prevented mortality following infection with laboratory-adapted and pandemic strains of IAV, without compromising antiviral adaptive immune responses or impeding viral clearance. UH15-38 displayed robust therapeutic efficacy even when administered late in the course of infection, suggesting that RIPK3 blockade may provide clinical benefit in patients with IAV-driven ARDS and other hyper-inflammatory pathologies.

Cost-Effectiveness Analysis of Implantable Cardioverter Defibrillator Therapy for Primary Prevention Patients with Additional Risk Factors in Brazil

Abstract Background: Implantable cardiac defibrillators (ICDs) therapy for primary prevention (PP) of sudden cardiac arrest (SCA) is well-established but underutilized globally. The Improve SCA study has identified a cohort of patients called 1.5 primary prevention (1.5PP), based on PP patients with the presence of documented risk factors: non-sustained ventricular tachycardia, frequent premature ventricular contractions, left ventricular ejection fraction < 25%, and pre-syncope or syncope. Objective: This study evaluated the cost-effectiveness of ICD therapy compared to no ICD among 1.5PP patients in the Brazilian public healthcare system. Methods: Modified inputs to a published Markov model were applied to compare costs and outcomes of ICD therapy to no ICD therapy from the Brazilian payer's perspective. Mortality and utility estimates were obtained from the IMPROVE SCA trial. Additional effectiveness inputs were sourced from the literature. Cost inputs were obtained from the Brazilian Unified Health System and the Ministry of Health. Costs were discounted at 4.7%; quality-adjusted life years (QALYs) were discounted at 1.45%. This study applied a willingness-to-pay (WTP) value of three times Brazil's gross domestic product (GDP) in 2017, R$105,723 (Brazilian Real). Results: The total discounted lifetime costs for ICD therapy were R$100,920 compared to R$43,866 for no ICD therapy. Total discounted QALYs for ICD therapy and no ICD therapy were 9.85 and 7.15, respectively. The incremental cost effectiveness ratio was R$21,156 per QALY and less than the R$105,723 WTP threshold. Results from sensitivity analyses were consistent with base case results. Conclusions: ICD therapy compared to no ICD therapy is cost-effective in the 1.5PP population in Brazil. (Int J Cardiovasc Sci. 2021; [online].ahead print, PP.0-0)

Growth performance and carcass quality are not different between pigs fed diets containing cold-fermented low-oil DDGS and pigs fed conventional DDGS, but pelleting improves gain to feed ratio regardless of source of DDGS.

The objective of this study was to test the hypothesis that growth performance and carcass characteristics of pigs fed diets containing cold-fermented, low oil distillers dried grains with solubles (DDGS) is not different from that of pigs fed diets containing conventional DDGS regardless of the physical form of the diets. A total of 160 barrows and gilts were used. There were 4 diets, 10 pens per diet, and 4 pigs per pen. Pigs were weaned at 21 d of age and fed a common phase 1 diet that did not contain DDGS during the initial 7 d post-weaning. Pigs were then allotted to the four diets that were arranged in a 2 × 2 factorial design with two sources of DDGS (cold-fermented and conventional DDGS) and two diet forms (meal and pellets). Pigs were fed phase 2 diets from day 7 to 21 and phase 3 diets from day 21 to 43 post-weaning. All diets were based on corn and soybean meal, but phase 2 diets also contained 15% DDGS and phase 3 diets contained 30% DDGS. From day 43, pigs were fed grower diets for 38 d, early finisher diets for 38 d, and late finisher diets for 18 d and these diets also contained 30% DDGS. Feed was provided on an ad libitum basis and daily feed allotments were recorded. Pigs were weighed at the beginning of each phase and at the conclusion of the experiment. On the last day of the experiment, the pig in each pen with a body weight that was closest to the pen average was slaughtered and carcass measurements were determined. Combined results for the two nursery phases indicated that feeding meal diets instead of pelleted diets increased (P < 0.001) average daily feed intake and decreased (P < 0.05) gain to feed ratio (G:F). However, no differences between the two sources of DDGS were observed for the overall growth performance of weanling pigs. For the entire growing-finishing period, the source of DDGS did not affect growth performance, but pigs fed meal diets had reduced (P < 0.001) G:F compared with pigs fed the pelleted diets. There were no differences between the two sources of DDGS for carcass characteristics. Back fat was greater (P < 0.05) for pigs fed pelleted diets than for pigs fed meal diets. In conclusion, no differences in growth performance or carcass characteristics between pigs fed cold-fermented DDGS and pigs fed conventional DDGS were observed. However, pigs fed pelleted diets had greater G:F and greater back fat than pigs fed meal diets.

Digestibility of amino acids, but not fiber, fat, or energy, is greater in cold-fermented, low-oil distillers dried grains with solubles (DDGS) compared with conventional DDGS fed to growing pigs.

Two experiments were conducted to test the hypothesis that the digestibility of gross energy (GE) and nutrients, and concentrations of digestible energy (DE) and metabolizable energy (ME) in two sources of distillers dried grains with solubles (DDGS) are not different despite different concentrations of fat in the two sources. Cold-fermented DDGS (6.82% fat) and a conventional DDGS (9.54% fat) were used. In experiment 1, 12 growing barrows (initial body weight = 55.2 ± 3.6 kg) that had a T-cannula installed in the distal ileum were allotted to one of three diets and two periods. Two diets contained either cold-fermented or conventional DDGS as the sole source of crude protein (CP) and amino acids (AA). The third diet was an N-free diet that was used to determine the basal endogenous losses of AA from the pigs. Each experimental period lasted 7 d and ileal digesta were collected on days 6 and 7 of each period. Results demonstrated that values for the standardized ileal digestibility (SID) of CP and most AA were greater (P < 0.05) or tended to be greater (P < 0.10) in cold-fermented than in conventional DDGS. In experiment 2, 24 barrows (initial body weight = 17.3 ± 1.3 kg) were randomly allotted to three diets with 8 replicate pigs per diet. A corn-based basal diet and two diets containing corn and either cold-fermented DDGS or conventional DDGS were formulated. Pigs were housed individually in metabolism crates and feces and urine were collected separately for 5 d after 7 d of adaptation. The apparent total tract digestibility (ATTD) of neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid-hydrolyzed ether extract (AEE) was greater (P < 0.01) in conventional DDGS than in cold-fermented DDGS, but there was no difference in ATTD of GE between the two sources of DDGS. However, conventional DDGS contained more (P < 0.001) DE and ME than cold-fermented DDGS because of greater GE. In conclusion, the SID of AA was greater in cold-fermented DDGS than in the conventional DDGS that was evaluated in this experiment, but the ATTD of NDF, ADF, and AEE, and ME were greater in conventional DDGS than in cold-fermented DDGS.

Evaluación del impacto de la terapia de resincronización cardiaca en pacientes de Latinoamérica / Evaluation of the impact of cardiac resynchronisation on patients Latin America

Resumen Objetivo: medir el impacto de la terapia de resincronización cardiaca en términos de variables ecocardiográficas en pacientes de países latinoamericanos. Método: se realizó un estudio prospectivo, multicéntrico, intervencionista, en el que los pacientes elegibles fueron llevados, por primera vez, a implante de un dispositivo de resincronización cardiaca. El objetivo primario fue valorar los cambios del tamaño y la función del ventrículo izquierdo por medio de un ecocardiograma previo al implante del dispositivo y en el sexto mes. Los objetivos secundarios evaluados fueron hospitalizaciones, cambios en la clase funcional, mortalidad, calidad de vida y un score compuesto clínico basado en estos factores de evaluación global del paciente. Resultados: para cumplir el objetivo primario se analizaron datos de 75 sujetos. La edad promedio fue de 63,7 años; 21.3% fueron mujeres y 30.7% tuvieron cardiopatía isquémica. Al sexto mes de seguimiento las mediciones de volumen de fin de diástole y sístole del ventrículo izquierdo disminuyeron en promedio 37.6 ml y 37.8 ml, respectivamente. La fracción de eyección del ventrículo izquierdo en promedio se incrementó un 11%. El puntaje compuesto clínico mostró mejoría en el 86.4% de los pacientes en el sexto mes postimplante del resincronizador. Conclusiones: se observó remodelado inverso del ventrículo izquierdo y mejoría en el estado clínico de los pacientes con insuficiencia cardiaca y disfunción sistólica del ventrículo izquierdo que recibieron terapia de resincronización cardiaca en el ámbito de la práctica clínica de rutina.

Abstract Objective: To measure the impact of cardiac resynchronisation therapy in terms of cardiac ultrasound variables in patients from Latin-American countries. Method: A prospective, multicentre, interventionist study was conducted, in which the eligible patients were those that had a cardiac resynchronisation device implanted for the first time. The primary objective was to assess the changes in size and left ventricular function by means of a cardiac ultrasound carried out prior to implanting the device and in the sixth month. The secondary objectives evaluated were hospital admissions, change in functional class, mortality, quality of life, and an overall assessment of the patient using a combined clinical score based on these factors. Results: A total of 75 subjects were analysed in order to complete the primary objective. The mean age was 63.7 years; 21.3% were female, and 30.7% had ischaemic heart disease. At the sixth month, the left ventricular end-diastolic and systolic volume decreased by a mean of 37.6 ml and 37.8 ml, respectively. The left ventricular ejection fraction increased by a mean of 11%. The combined clinical score showed an improvement in 86.4% of the patients in the sixth month after the implantation of the synchronisation device. Conclusions: A reverse remodelling of the left ventricle was observed, as well as an improvement in the clinical stage of patients with heart failure and left ventricular systolic dysfunction that received cardiac resynchronisation treatment in the setting of routine clinical practice.

Caspase-8-Dependent Inflammatory Responses Are Controlled by Its Adaptor, FADD, and Necroptosis.

Cell death pathways regulate various homeostatic processes. Autoimmune lymphoproliferative syndrome (ALPS) in humans and lymphoproliferative (LPR) disease in mice result from abrogated CD95-induced apoptosis. Because caspase-8 mediates CD95 signaling, we applied genetic approaches to dissect the roles of caspase-8 in cell death and inflammation. Here, we describe oligomerization-deficient Caspase-8F122GL123G/F122GL123G and non-cleavable Caspase-8D387A/D387A mutant mice with defective caspase-8-mediated apoptosis. Although neither mouse developed LPR disease, removal of the necroptosis effector Mlkl from Caspase-8D387A/D387A mice revealed an inflammatory role of caspase-8. Ablation of one allele of Fasl, Fadd, or Ripk1 prevented the pathology of Casp8D387A/D387AMlkl-/- animals. Removing both Fadd alleles from these mice resulted in early lethality prior to post-natal day 15 (P15), which was prevented by co-ablation of either Ripk1 or Caspase-1. Our results suggest an in vivo role of the inflammatory RIPK1-caspase-8-FADD (FADDosome) complex and reveal a FADD-independent inflammatory role of caspase-8 that involves activation of an inflammasome.

Influenza Virus Z-RNAs Induce ZBP1-Mediated Necroptosis.

Influenza A virus (IAV) is a lytic RNA virus that triggers receptor-interacting serine/threonine-protein kinase 3 (RIPK3)-mediated pathways of apoptosis and mixed lineage kinase domain-like pseudokinase (MLKL)-dependent necroptosis in infected cells. ZBP1 initiates RIPK3-driven cell death by sensing IAV RNA and activating RIPK3. Here, we show that replicating IAV generates Z-RNAs, which activate ZBP1 in the nucleus of infected cells. ZBP1 then initiates RIPK3-mediated MLKL activation in the nucleus, resulting in nuclear envelope disruption, leakage of DNA into the cytosol, and eventual necroptosis. Cell death induced by nuclear MLKL was a potent activator of neutrophils, a cell type known to drive inflammatory pathology in virulent IAV disease. Consequently, MLKL-deficient mice manifest reduced nuclear disruption of lung epithelia, decreased neutrophil recruitment into infected lungs, and increased survival following a lethal dose of IAV. These results implicate Z-RNA as a new pathogen-associated molecular pattern and describe a ZBP1-initiated nucleus-to-plasma membrane "inside-out" death pathway with potentially pathogenic consequences in severe cases of influenza.

ZBP1/DAI Drives RIPK3-Mediated Cell Death Induced by IFNs in the Absence of RIPK1.

Receptor-interacting protein kinase 1 (RIPK1) regulates cell fate and proinflammatory signaling downstream of multiple innate immune pathways, including those initiated by TNF-α, TLR ligands, and IFNs. Genetic ablation of Ripk1 results in perinatal lethality arising from both RIPK3-mediated necroptosis and FADD/caspase-8-driven apoptosis. IFNs are thought to contribute to the lethality of Ripk1-deficient mice by activating inopportune cell death during parturition, but how IFNs activate cell death in the absence of RIPK1 is not understood. In this study, we show that Z-form nucleic acid binding protein 1 (ZBP1; also known as DAI) drives IFN-stimulated cell death in settings of RIPK1 deficiency. IFN-activated Jak/STAT signaling induces robust expression of ZBP1, which complexes with RIPK3 in the absence of RIPK1 to trigger RIPK3-driven pathways of caspase-8-mediated apoptosis and MLKL-driven necroptosis. In vivo, deletion of either Zbp1 or core IFN signaling components prolong viability of Ripk1-/- mice for up to 3 mo beyond parturition. Together, these studies implicate ZBP1 as the dominant activator of IFN-driven RIPK3 activation and perinatal lethality in the absence of RIPK1.

Improving the utilization of implantable cardioverter defibrillators for sudden cardiac arrest prevention (Improve SCA) in developing countries: Clinical characteristics and reasons for implantation refusal.

BACKGROUND: Despite available evidence that implantable cardioverter defibrillators (ICDs) reduce all-cause mortality among patients at risk for sudden cardiac death, utilization of ICDs is low especially in developing countries. OBJECTIVE: To summarize reasons for ICD or cardiac resynchronization therapy defibrillator implant refusal by patients at risk for sudden cardiac arrest (Improve SCA) in developing countries. METHODS: Primary prevention (PP) and secondary prevention (SP) patients from countries where ICD use is low were enrolled. PP patients with additional risk factors (syncope, ejection fraction < 25%, nonsustained ventricular tachycardia [NSVT], or frequent premature ventricular complexes) were further categorized as "1.5 PP patients." Candidates who declined implantation were asked for reasons for refusal. Baseline factors that may have influenced the implant decision were examined using logistic regression. RESULTS: Among 3892 patients, the implant refusal rate was 46.5% among PP patients (n = 2700), and 10.3% among SP patients (n = 1192). The most common refusal reason was inability to pay for the device (53.8%), followed by not believing in the benefits of the ICD (19.4%). Among PP ICD candidates, those with no syncope, no NSVT, no premature ventricular contractions, shorter QRS duration, no atrial arrhythmias, and no left bundle branch block were more likely to refuse implant. Among SP candidates, a history of cardiovascular surgery and no sinus node dysfunction were significant predictors of ICD refusal. Additionally, countries had significant differences in patient refusal rates among PP and SP groups. CONCLUSION: Implant refusal among PP patients is high in many countries. Increased reimbursement and better awareness of the benefits of an ICD could increase their utilization.

Generation and Use of Chimeric RIP Kinase Molecules to Study Necroptosis.

Necroptosis, a form of regulated necrosis, is triggered by a variety of signals that converge to activate receptor interacting protein kinase-3 (RIPK3), consequently promoting the direct phosphorylation and activation of the mixed lineage kinase like (MLKL) protein. Active MLKL executes necroptosis by disrupting the integrity of the plasma membrane. Stimuli that can induce necroptosis include ligation of death receptors (a subset of the TNFR family), toll-like receptors (in particular, TLR3 and TLR4), interferons, and the intracellular viral sensor, DAI/ZBP1, among others. To study the process in more detail, it is useful to have a means to directly activate RIPK3. Here we provide protocols and procedures to artificially induce necroptotic cell death by drug-induced forced dimerization of RIPK3. We also provide information on specific kinase inhibitors, procedures to monitor RIPK3 and MLKL activation, and real-time quantification of cell death.

Aproximación Neurodinámica a la Cognición Social / Neurodimanic Approach to Social Cognition

En las últimas décadas ha crecido el estudio los mecanismos involucrados en el comportamiento social, gran parte de estas indagaciones se han realizado desde una aproximación de la neurociencia social cognitiva, la cual se basa en un modelo representacional del procesamiento de información. No obstante, esta aproximación ha sido ampliamente criticada por desconocer la participación del cuerpo, la dinámica afectiva, el contexto social, el cambio durante el desarrollo y suponer un procesamiento modular endógeno. En este sentido, este artículo presenta un modelo neurodinámico de la cognición social (CS), comprendiéndola desde una aproximación enactiva, situada, relacional y sistémica. Desde este modelo se describen los principales cambios en esperados la actividad cerebral durante las interacciones sociales en tiempo real y durante la ontogenia. Se concluye resaltando los desafíos y oportunidades que este tipo de aproximaciones puede proporcionar a la neurociencia y psicología social del futuro.

In recent decades it has seen a growing interest to study the mechanisms involved in social behavior, much of these inquiries fall within social cognitive neuroscience approach, which is based on a representational model of information processing. However, this approach has been widely criticized for ignoring the body participation, emotional dynamics, social context, developmental changes and assuming an endogenous modular processing. In this regard, this article presents a neurodynamic model of social cognition, which understand social process from an enactive, embodied, situated, relational and systemic perspective. This model let us described the main expected changes in brain activity during ongoing social interactions and ontogeny. The conclusion highlights the challenges and opportunities that this kind of approach can provide for a coming neuroscience and social psychology.

RIPK3 Activates Parallel Pathways of MLKL-Driven Necroptosis and FADD-Mediated Apoptosis to Protect against Influenza A Virus.

Influenza A virus (IAV) is a lytic virus in primary cultures of many cell types and in vivo. We report that the kinase RIPK3 is essential for IAV-induced lysis of mammalian fibroblasts and lung epithelial cells. Replicating IAV drives assembly of a RIPK3-containing complex that includes the kinase RIPK1, the pseudokinase MLKL, and the adaptor protein FADD, and forms independently of signaling by RNA-sensing innate immune receptors (RLRs, TLRs, PKR), or the cytokines type I interferons and TNF-α. Downstream of RIPK3, IAV activates parallel pathways of MLKL-driven necroptosis and FADD-mediated apoptosis, with the former reliant on RIPK3 kinase activity and neither on RIPK1 activity. Mice deficient in RIPK3 or doubly deficient in MLKL and FADD, but not MLKL alone, are more susceptible to IAV than their wild-type counterparts, revealing an important role for RIPK3-mediated apoptosis in antiviral immunity. Collectively, these results outline RIPK3-activated cytolytic mechanisms essential for controlling respiratory IAV infection.

Sequential Engagement of Distinct MLKL Phosphatidylinositol-Binding Sites Executes Necroptosis.

Necroptosis is a cell death pathway regulated by the receptor interacting protein kinase 3 (RIPK3) and the mixed lineage kinase domain-like (MLKL) pseudokinase. How MLKL executes plasma membrane rupture upon phosphorylation by RIPK3 remains controversial. Here, we characterize the hierarchical transduction of structural changes in MLKL that culminate in necroptosis. The MLKL brace, proximal to the N-terminal helix bundle (NB), is involved in oligomerization to facilitate plasma membrane targeting through the low-affinity binding of NB to phosphorylated inositol polar head groups of phosphatidylinositol phosphate (PIP) phospholipids. At the membrane, the NB undergoes a "rolling over" mechanism to expose additional higher-affinity PIP-binding sites responsible for robust association to the membrane and displacement of the brace from the NB. PI(4,5)P2 is the preferred PIP-binding partner. We investigate the specific association of MLKL with PIPs and subsequent structural changes during necroptosis.

Oxidative stress, redox signaling pathways, and autophagy in cachectic muscles of male patients with advanced COPD and lung cancer.

Muscle dysfunction and wasting are predictors of mortality in advanced COPD and malignancies. Redox imbalance and enhanced protein catabolism are underlying mechanisms in COPD. We hypothesized that the expression profile of several biological markers share similarities in patients with cachexia associated with either COPD or lung cancer (LC). In vastus lateralis of cachectic patients with either LC (n=10) or advanced COPD (n=16) and healthy controls (n=10), markers of redox balance, inflammation, proteolysis, autophagy, signaling pathways, mitochondrial function, muscle structure, and sarcomere damage were measured using laboratory and light and electron microscopy techniques. Systemic redox balance and inflammation were also determined. All subjects were clinically evaluated. Compared to controls, in both cachectic groups of patients, a similar expression profile of different biological markers was observed in their muscles: increased levels of muscle protein oxidation and ubiquitination (p<0.05, both), which positively correlated (r=0.888), redox-sensitive signaling pathways (NF-κB and FoxO) were activated (p<0.05, all), fast-twitch fiber sizes were atrophied, muscle structural abnormalities and sarcomere disruptions were significantly greater (p<0.05, both). Structural and functional protein levels were lower in muscles of both cachectic patient groups than in controls (p<0.05, all). However, levels of autophagy markers including ultrastructural autophagosome counts were increased only in muscles of cachectic COPD patients (p<0.05). Systemic oxidative stress and inflammation levels were also increased in both patient groups compared to controls (p<0.005, both). Oxidative stress and redox-sensitive signaling pathways are likely to contribute to the etiology of muscle wasting and sarcomere disruption in patients with respiratory cachexia: LC and COPD.

Survivin expression promotes VEGF-induced tumor angiogenesis via PI3K/Akt enhanced ß-catenin/Tcf-Lef dependent transcription.

Early in cancer development, tumour cells express vascular endothelial growth factor (VEGF), a secreted molecule that is important in all stages of angiogenesis, an essential process that provides nutrients and oxygen to the nascent tumor and thereby enhances tumor-cell survival and facilitates growth. Survivin, another protein involved in angiogenesis, is strongly expressed in most human cancers, where it promotes tumor survival by reducing apoptosis as well as favoring endothelial cell proliferation and migration. The mechanisms by which cancer cells induce VEGF expression and angiogenesis upon survivin up-regulation remain to be fully established. Since the PI3K/Akt signalling and ß-catenin-Tcf/Lef dependent transcription have been implicated in the expression of many cancer-related genes, including survivin and VEGF, we evaluated whether survivin may favor VEGF expression, release from tumor cells and induction of angiogenesis in a PI3K/Akt-ß-catenin-Tcf/Lef-dependent manner. Here, we provide evidence linking survivin expression in tumor cells to increased ß-catenin protein levels, ß-catenin-Tcf/Lef transcriptional activity and expression of several target genes of this pathway, including survivin and VEGF, which accumulates in the culture medium. Alternatively, survivin downregulation reduced ß-catenin protein levels and ß-catenin-Tcf/Lef transcriptional activity. Also, using inhibitors of PI3K and the expression of dominant negative Akt, we show that survivin acts upstream in an amplification loop to promote VEGF expression. Moreover, survivin knock-down in B16F10 murine melanoma cells diminished the number of blood vessels and reduced VEGF expression in tumors formed in C57BL/6 mice. Finally, in the chick chorioallantoid membrane assay, survivin expression in tumor cells enhanced VEGF liberation and blood vessel formation. Importantly, the presence of neutralizing anti-VEGF antibodies precluded survivin-enhanced angiogenesis in this assay. These findings provide evidence for the existance of a posititve feedback loop connecting survivin expression in tumor cells to PI3K/Akt enhanced ß-catenin-Tcf/Lef-dependent transcription followed by secretion of VEGF and angiogenesis.

RIPK1 blocks early postnatal lethality mediated by caspase-8 and RIPK3.

Receptor-interacting protein kinase (RIPK)-1 is involved in RIPK3-dependent and -independent signaling pathways leading to cell death and/or inflammation. Genetic ablation of ripk1 causes postnatal lethality, which was not prevented by deletion of ripk3, caspase-8, or fadd. However, animals that lack RIPK1, RIPK3, and either caspase-8 or FADD survived weaning and matured normally. RIPK1 functions in vitro to limit caspase-8-dependent, TNFR-induced apoptosis, and animals lacking RIPK1, RIPK3, and TNFR1 survive to adulthood. The role of RIPK3 in promoting lethality in ripk1(-/-) mice suggests that RIPK3 activation is inhibited by RIPK1 postbirth. Whereas TNFR-induced RIPK3-dependent necroptosis requires RIPK1, cells lacking RIPK1 were sensitized to necroptosis triggered by poly I:C or interferons. Disruption of TLR (TRIF) or type I interferon (IFNAR) signaling delayed lethality in ripk1(-/-)tnfr1(-/-) mice. These results clarify the complex roles for RIPK1 in postnatal life and provide insights into the regulation of FADD-caspase-8 and RIPK3-MLKL signaling by RIPK1.

Protective roles for caspase-8 and cFLIP in adult homeostasis.

Caspase-8 or cellular FLICE-like inhibitor protein (cFLIP) deficiency leads to embryonic lethality in mice due to defects in endothelial tissues. Caspase-8(-/-) and receptor-interacting protein kinase-3 (RIPK3)(-/-), but not cFLIP(-/-) and RIPK3(-/-), double-knockout animals develop normally, indicating that caspase-8 antagonizes the lethal effects of RIPK3 during development. Here, we show that the acute deletion of caspase-8 in the gut of adult mice induces enterocyte death, disruption of tissue homeostasis, and inflammation, resulting in sepsis and mortality. Likewise, acute deletion of caspase-8 in a focal region of the skin induces local keratinocyte death, tissue disruption, and inflammation. Strikingly, RIPK3 ablation rescues both phenotypes. However, acute loss of cFLIP in the skin produces a similar phenotype that is not rescued by RIPK3 ablation. TNF neutralization protects from either acute loss of caspase-8 or cFLIP. These results demonstrate that caspase-8-mediated suppression of RIPK3-induced death is required not only during development but also for adult homeostasis. Furthermore, RIPK3-dependent inflammation is dispensable for the skin phenotype.

Sildenafil to improve respiratory rehabilitation outcomes in COPD: a controlled trial.

Pulmonary hypertension is a serious complication of chronic obstructive pulmonary disease (COPD) that currently has no established pharmacological treatment. This study aimed to assess whether concomitant treatment with sildenafil would enhance the results of pulmonary rehabilitation in patients with COPD and increased pulmonary arterial pressure (PAP). In this double-blind, randomised controlled trial patients received 20 mg sildenafil or placebo three times daily and underwent pulmonary rehabilitation for 3 months. The primary end-point was the gain in the cycle endurance time at a constant work-rate. Secondary end-points included performance in the incremental exercise test, 6-min walk distance and quality of life. 63 patients with severe COPD and moderately increased PAP were randomised. Cycle endurance time increased by 149 s (95% CI 26-518 s) in the sildenafil group and by 169 s (95% CI 0-768 s) in the placebo group (median change difference -7 s, 95% CI -540-244 s; p=0.77). Gains in the incremental exercise test, 6-min walk distance and quality of life at the end of the study did not differ between groups. Measurements of arterial oxygenation and adverse events were similar in both groups. In patients with severe COPD and moderately increased PAP, concomitant treatment with sildenafil does not improve the results of pulmonary rehabilitation in exercise tolerance.

BH3-only proteins are part of a regulatory network that control the sustained signalling of the unfolded protein response sensor IRE1α.

Adaptation to endoplasmic reticulum (ER) stress depends on the activation of the unfolded protein response (UPR) stress sensor inositol-requiring enzyme 1α (IRE1α), which functions as an endoribonuclease that splices the mRNA of the transcription factor XBP-1 (X-box-binding protein-1). Through a global proteomic approach we identified the BCL-2 family member PUMA as a novel IRE1α interactor. Immun oprecipitation experiments confirmed this interaction and further detected the association of IRE1α with BIM, another BH3-only protein. BIM and PUMA double-knockout cells failed to maintain sustained XBP-1 mRNA splicing after prolonged ER stress, resulting in early inactivation. Mutation in the BH3 domain of BIM abrogated the physical interaction with IRE1α, inhibiting its effects on XBP-1 mRNA splicing. Unexpectedly, this regulation required BCL-2 and was antagonized by BAD or the BH3 domain mimetic ABT-737. The modulation of IRE1α RNAse activity by BH3-only proteins was recapitulated in a cell-free system suggesting a direct regulation. Moreover, BH3-only proteins controlled XBP-1 mRNA splicing in vivo and affected the ER stress-regulated secretion of antibodies by primary B cells. We conclude that a subset of BCL-2 family members participates in a new UPR-regulatory network, thus assuming apoptosis-unrelated functions.