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Pyroptosis is a lytic cell death mode that helps limit the spread of infections and is also linked to pathology in sterile inflammatory diseases and autoimmune diseases1-4. During pyroptosis, inflammasome activation and the engagement of caspase-1 lead to cell death, along with the maturation and secretion of the inflammatory cytokine interleukin-1ß (IL-1ß). The dominant effect of IL-1ß in promoting tissue inflammation has clouded the potential influence of other factors released from pyroptotic cells. Here, using a system in which macrophages are induced to undergo pyroptosis without IL-1ß or IL-1α release (denoted Pyro-1), we identify unexpected beneficial effects of the Pyro-1 secretome. First, we noted that the Pyro-1 supernatants upregulated gene signatures linked to migration, cellular proliferation and wound healing. Consistent with this gene signature, Pyro-1 supernatants boosted migration of primary fibroblasts and macrophages, and promoted faster wound closure in vitro and improved tissue repair in vivo. In mechanistic studies, lipidomics and metabolomics of the Pyro-1 supernatants identified the presence of both oxylipins and metabolites, linking them to pro-wound-healing effects. Focusing specifically on the oxylipin prostaglandin E2 (PGE2), we find that its synthesis is induced de novo during pyroptosis, downstream of caspase-1 activation and cyclooxygenase-2 activity; further, PGE2 synthesis occurs late in pyroptosis, with its release dependent on gasdermin D pores opened during pyroptosis. As for the pyroptotic metabolites, they link to immune cell infiltration into the wounds, and polarization to CD301+ macrophages. Collectively, these data advance the concept that the pyroptotic secretome possesses oxylipins and metabolites with tissue repair properties that may be harnessed therapeutically.
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Macrófagos , Oxilipinas , Piroptosis , Secretoma , Cicatrización de Heridas , Animales , Femenino , Humanos , Ratones , Caspasa 1/metabolismo , Movimiento Celular , Proliferación Celular , Ciclooxigenasa 2/metabolismo , Dinoprostona/biosíntesis , Dinoprostona/metabolismo , Fibroblastos/metabolismo , Fibroblastos/citología , Gasderminas/metabolismo , Inflamasomas/metabolismo , Interleucina-1beta , Lipidómica , Macrófagos/metabolismo , Macrófagos/citología , Ratones Endogámicos C57BL , Oxilipinas/metabolismo , Proteínas de Unión a Fosfato/metabolismo , Secretoma/metabolismo , Cicatrización de Heridas/fisiologíaRESUMEN
Regulated cell death is an integral part of life, and has broad effects on organism development and homeostasis1. Malfunctions within the regulated cell death process, including the clearance of dying cells, can manifest in diverse pathologies throughout various tissues including the gastrointestinal tract2. A long appreciated, yet elusively defined relationship exists between cell death and gastrointestinal pathologies with an underlying microbial component3-6, but the direct effect of dying mammalian cells on bacterial growth is unclear. Here we advance a concept that several Enterobacteriaceae, including patient-derived clinical isolates, have an efficient growth strategy to exploit soluble factors that are released from dying gut epithelial cells. Mammalian nutrients released after caspase-3/7-dependent apoptosis boosts the growth of multiple Enterobacteriaceae and is observed using primary mouse colonic tissue, mouse and human cell lines, several apoptotic triggers, and in conventional as well as germ-free mice in vivo. The mammalian cell death nutrients induce a core transcriptional response in pathogenic Salmonella, and we identify the pyruvate formate-lyase-encoding pflB gene as a key driver of bacterial colonization in three contexts: a foodborne infection model, a TNF- and A20-dependent cell death model, and a chemotherapy-induced mucositis model. These findings introduce a new layer to the complex host-pathogen interaction, in which death-induced nutrient release acts as a source of fuel for intestinal bacteria, with implications for gut inflammation and cytotoxic chemotherapy treatment.
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Apoptosis , Enterobacteriaceae/crecimiento & desarrollo , Enterobacteriaceae/metabolismo , Células Epiteliales/citología , Células Epiteliales/metabolismo , Intestinos/citología , Intestinos/microbiología , Acetiltransferasas/genética , Acetiltransferasas/metabolismo , Animales , Caspasa 3/metabolismo , Caspasa 7/metabolismo , Línea Celular , Modelos Animales de Enfermedad , Células Epiteliales/patología , Femenino , Enfermedades Transmitidas por los Alimentos/microbiología , Vida Libre de Gérmenes , Interacciones Huésped-Patógeno , Inflamación/metabolismo , Inflamación/microbiología , Inflamación/patología , Masculino , Ratones , Mucositis/inducido químicamente , Salmonella/enzimología , Salmonella/genética , Salmonella/crecimiento & desarrollo , Salmonella/metabolismo , Transcriptoma , Proteína 3 Inducida por el Factor de Necrosis Tumoral alfa/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
BACKGROUND: Reversal of neuromuscular blockade (NMB) with sugammadex can cause marked bradycardia and asystole. Administration of sugammadex typically occurs in a dynamic period when anesthetic adjuvants and gas concentrations are being titrated to achieve emergence. This evaluation examined the heart rate (HR) responses to sugammadex to reverse moderate to deep NMB during a steady-state period and sought mechanisms for HR changes. METHODS: Patients with normal sinus rhythm, who were undergoing elective surgery that included rocuronium for NMB, were evaluated. After surgery, while at steady-state surgical depth anesthesia with sevoflurane and mechanical ventilation, patients received either placebo or 2 or 4 mg/kg of sugammadex to reverse moderate to deep NMB. Study personnel involved in data analysis were blinded to treatment. Continuous electrocardiogram (ECG) was recorded from the 5 minutes before and 5 minutes after sugammadex/placebo administration. R-R intervals were converted to HR and averaged in 1-minute increments. The maximum prolongation of an R-R interval after sugammadex was converted to an instantaneous HR. RESULTS: A total of 63 patients were evaluated: 8 received placebo, and 38 and 17 received 2 and 4 mg/kg sugammadex. Age, body mass index, and patient factors were similar in groups. Placebo did not elicit HR changes, whereas sugammadex caused maximum instantaneous HR slowing (calculated from the longest R-R interval), ranging from 2 to 19 beats/min. There were 7 patients with maximum HR slowing >10 beats/min. The average HR change and 95% confidence interval (CI) during the 5 minutes after 2 mg/kg sugammadex were 3.1 (CI, 2.3-4.1) beats/min, and this was not different from the 4 mg/kg sugammadex group (4.1 beats/min [CI, 2.5-5.6]). HR variability derived from the standard deviation of consecutive R-R intervals increased after sugammadex. CONCLUSIONS: Sugammadex to reverse moderate and deep NMB resulted in a fast onset and variable magnitude of HR slowing in patients. A difference in HR slowing as a function of dose did not achieve statistical significance. The observational nature of the investigation prevented a full understanding of the mechanism(s) of the HR slowing.
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Anestésicos , Bloqueo Neuromuscular , Fármacos Neuromusculares no Despolarizantes , gamma-Ciclodextrinas , Adyuvantes Anestésicos , Androstanoles , Frecuencia Cardíaca , Humanos , Bloqueo Neuromuscular/efectos adversos , Bloqueo Neuromuscular/métodos , Fármacos Neuromusculares no Despolarizantes/efectos adversos , Rocuronio , Sevoflurano , Sugammadex , gamma-Ciclodextrinas/efectos adversosRESUMEN
Fast radio bursts are bright, unresolved, non-repeating, broadband, millisecond flashes, found primarily at high Galactic latitudes, with dispersion measures much larger than expected for a Galactic source. The inferred all-sky burst rate is comparable to the core-collapse supernova rate out to redshift 0.5. If the observed dispersion measures are assumed to be dominated by the intergalactic medium, the sources are at cosmological distances with redshifts of 0.2 to 1 (refs 10 and 11). These parameters are consistent with a wide range of source models. One fast burst revealed circular polarization of the radio emission, but no linear polarization was detected, and hence no Faraday rotation measure could be determined. Here we report the examination of archival data revealing Faraday rotation in the fast radio burst FRB 110523. Its radio flux and dispersion measure are consistent with values from previously reported bursts and, accounting for a Galactic contribution to the dispersion and using a model of intergalactic electron density, we place the source at a maximum redshift of 0.5. The burst has a much higher rotation measure than expected for this line of sight through the Milky Way and the intergalactic medium, indicating magnetization in the vicinity of the source itself or within a host galaxy. The pulse was scattered by two distinct plasma screens during propagation, which requires either a dense nebula associated with the source or a location within the central region of its host galaxy. The detection in this instance of magnetization and scattering that are both local to the source favours models involving young stellar populations such as magnetars over models involving the mergers of older neutron stars, which are more likely to be located in low-density regions of the host galaxy.
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Intensity mapping of the 21 cm line has arisen as a powerful probe of the high-redshift Universe, but its potential is limited by extremely bright foregrounds and high source confusion. We propose a new analysis which can help solve both problems. From the combination of an intensity map with an overlapping galaxy survey, we construct a new one-point statistic which is unbiased by foregrounds and contains information left out of conventional analyses. We show that our method can measure the HI mass function with unprecedented precision using observations similar to recent 21 cm detections.
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Ethanolamine is a ubiquitous and essential molecule within a host. Significantly, bacterial pathogens exploit ethanolamine during infection to promote growth and regulate virulence. The ethanolamine permease EutH is dispensable for growth in vitro under standard conditions, whereas EutH is required for ethanolamine utilization at low pH. These findings suggested a model in which EutH facilitates diffusion of ethanolamine into the bacterial cell in acidic environments. To date, the ecological significance of this model has not been thoroughly investigated, and the importance of EutH to bacterial growth under physiologically relevant conditions is not known. During infection, immune cells internalize invading bacteria within an acidic, nutrient-depleted vacuole called the phagosome. Here, we investigated the hypothesis that EutH promotes bacterial survival following phagocytosis. Our findings indicate that EutH is important for survival and replication of the facultative intracellular pathogens Salmonella enterica serovar Typhimurium and Listeria monocytogenes during prolonged or transient exposure to the phagosome, respectively. Furthermore, in agreement with EutH being important in the acidic environment, neutralization of the vacuole abolished the requirement for EutH. Significantly, consistent with a role for EutH in promoting intramacrophage survival, EutH was not required during S Typhimurium local intestinal infection but specifically conferred an advantage upon dissemination to peripheral organs. These findings reveal a physiologically relevant and conserved role for EutH in spatiotemporal niche adaptation during infection.
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Proteínas Bacterianas/fisiología , Transporte Biológico/fisiología , Etanolaminas/metabolismo , Listeria monocytogenes/patogenicidad , Macrófagos/patología , Salmonella enterica/patogenicidad , Vacuolas/microbiologíaRESUMEN
Chemical and nutrient signaling are fundamental for all cellular processes, including interactions between the mammalian host and the microbiota, which have a significant impact on health and disease. Ethanolamine is an essential component of cell membranes and has profound signaling activity within mammalian cells by modulating inflammatory responses and intestinal physiology. Here, we describe a virulence-regulating pathway in which the foodborne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) exploits ethanolamine signaling to recognize and adapt to distinct niches within the host. The bacterial transcription factor EutR promotes ethanolamine metabolism in the intestine, which enables S. Typhimurium to establish infection. Subsequently, EutR directly activates expression of the Salmonella pathogenicity island 2 in the intramacrophage environment, and thus augments intramacrophage survival. Moreover, EutR is critical for robust dissemination during mammalian infection. Our findings reveal that S. Typhimurium co-opts ethanolamine as a signal to coordinate metabolism and then virulence. Because the ability to sense ethanolamine is a conserved trait among pathogenic and commensal bacteria, our work indicates that ethanolamine signaling may be a key step in the localized adaptation of bacteria within their mammalian hosts.
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Adaptación Biológica , Etanolamina/metabolismo , Regulación Bacteriana de la Expresión Génica/genética , Salmonelosis Animal/metabolismo , Salmonelosis Animal/microbiología , Salmonella typhimurium , Transducción de Señal , Adaptación Biológica/inmunología , Animales , Islas Genómicas/inmunología , Humanos , Salmonella typhimurium/patogenicidad , Virulencia/genética , Factores de Virulencia/metabolismoRESUMEN
BACKGROUND: Enhancing a medical school curriculum with new men's health teaching and learning requires an understanding of the local capacity and the facilitators and barriers to implementing new content, and an approach that accommodates the systemic and cultural differences between medical schools. METHODS: A formative evaluation was undertaken to determine the perspectives of key informants (academics, curriculum developers) from four Australian medical schools about the strategies needed to enhance their curriculum with men's health teaching and learning. Through semi-structured questioning with 17 key informants, interviewees also described the contextual barriers and facilitators to incorporating new topic areas into existing curriculum. Interviews were recorded with consent, transcribed verbatim, and analysed by two researchers to identify key themes. RESULTS: Interviewees were enthusiastic about incorporating men's health content through a men's health curriculum framework but highlighted the need for systems to assist in identifying gaps in their current curriculum where the men's health topics could be integrated. The student experience was identified as a key driver for men's health teaching and learning. Furthermore, core men's health clinical outcomes needed to be defined and topic areas vertically integrated across the curricula. This would ensure that students were appropriately equipped with the skills and knowledge for subsequent clinical practice in a range of geographical settings. Interviewees consistently suggested that the best implementation strategy is to have someone 'on the ground' to work directly with medical school staff and champion the men's health discipline. Providing mechanisms for sharing knowledge and resources across medical schools was highlighted to facilitate implementation, particularly for those medical schools with limited men's health teaching resources. CONCLUSIONS: Despite the unanimous support for men's health teaching and learning, the evaluation highlighted that the student experience must be recognised as paramount when integrating new topic areas into an already packed curriculum. A community of practice, where medical schools share relevant resources and knowledge, could help to ensure a commonality of student experience with respect to men's health learning in medical schools across different geographical settings and with different levels of resourcing. Such an approach could also be adapted to other areas of curriculum enhancement.
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Curriculum , Educación de Pregrado en Medicina/organización & administración , Educación en Salud/organización & administración , Salud del Hombre , Australia , Femenino , Humanos , Aprendizaje/fisiología , Masculino , Evaluación de Programas y Proyectos de Salud , Investigación Cualitativa , Facultades de Medicina/organización & administración , Estudiantes de Medicina/estadística & datos numéricos , Enseñanza/métodos , Adulto JovenRESUMEN
Intestinal intraepithelial T lymphocytes (IEL) constitutively express high amounts of the cytotoxic proteases Granzymes (Gzm) A and B and are therefore thought to protect the intestinal epithelium against infection by killing infected epithelial cells. However, the role of IEL granzymes in a protective immune response has yet to be demonstrated. We show that GzmA and GzmB are required to protect mice against oral, but not intravenous, infection with Salmonella enterica serovar Typhimurium, consistent with an intestine-specific role. IEL-intrinsic granzymes mediate the protective effects by controlling intracellular bacterial growth and aiding in cell-intrinsic pyroptotic cell death of epithelial cells. Surprisingly, we found that both granzymes play non-redundant roles. GzmB-/- mice carried significantly lower burdens of Salmonella, as predominant GzmA-mediated cell death effectively reduced bacterial translocation across the intestinal barrier. Conversely, in GzmA-/- mice, GzmB-driven apoptosis favored luminal Salmonella growth by providing nutrients, while still reducing translocation across the epithelial barrier. Together, the concerted actions of both GzmA and GzmB balance cell death mechanisms at the intestinal epithelium to provide optimal control that Salmonella cannot subvert.
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The clearance of apoptotic cells, termed efferocytosis, is essential for tissue homeostasis and prevention of autoimmunity1. Although past studies have elucidated local molecular signals that regulate homeostatic efferocytosis in a tissue2,3, whether signals arising distally also regulate homeostatic efferocytosis remains elusive. Here, we show that large peritoneal macrophage (LPM) display impairs efferocytosis in broad-spectrum antibiotics (ABX)-treated, vancomycin-treated and germ-free mice in vivo, all of which have a depleted gut microbiota. Mechanistically, the microbiota-derived short-chain fatty acid butyrate directly boosts efferocytosis efficiency and capacity in mouse and human macrophages, and rescues ABX-induced LPM efferocytosis defects in vivo. Bulk messenger RNA sequencing of butyrate-treated macrophages in vitro and single-cell messenger RNA sequencing of LPMs isolated from ABX-treated and butyrate-rescued mice reveals regulation of efferocytosis-supportive transcriptional programmes. Specifically, we find that the efferocytosis receptor T cell immunoglobulin and mucin domain containing 4 (TIM-4, Timd4) is downregulated in LPMs of ABX-treated mice but rescued by oral butyrate. We show that TIM-4 is required for the butyrate-induced enhancement of LPM efferocytosis capacity and that LPM efferocytosis is impaired beyond withdrawal of ABX. ABX-treated mice exhibit significantly worse disease in a mouse model of lupus. Our results demonstrate that homeostatic efferocytosis relies on distal metabolic signals and suggest that defective homeostatic efferocytosis may explain the link between ABX use and inflammatory disease4-7.
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The spread of pandemic methicillin-resistant Staphylococcus aureus (MRSA) clones such as USA300 and EMRSA-15 is a global health concern. As a part of a surveillance study of three long-term care facilities in the Greater Chicago area, phenotypic and molecular characterization of nasal MRSA isolates was performed. We report a cluster of pandemic EMRSA-15, an MRSA clone rarely reported from the United States, detected during this study.
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The intestinal epithelium is a single cell layer that is constantly renewed and acts as a physical barrier that separates intestinal microbiota from underlying tissues. In inflammatory bowel disease (IBD) in humans, as well as in experimental mouse models of IBD, this barrier is impaired, causing microbial infiltration and inflammation. Deficiency in OTU deubiquitinase with linear linkage specificity (OTULIN) causes OTULIN-related autoinflammatory syndrome (ORAS), a severe inflammatory pathology affecting multiple organs including the intestine. We show that mice with intestinal epithelial cell (IEC)-specific OTULIN deficiency exhibit increased susceptibility to experimental colitis and are highly sensitive to TNF toxicity, due to excessive apoptosis of OTULIN deficient IECs. OTULIN deficiency also increases intestinal pathology in mice genetically engineered to secrete excess TNF, confirming that chronic exposure to TNF promotes epithelial cell death and inflammation in OTULIN deficient mice. Mechanistically we demonstrate that upon TNF stimulation, OTULIN deficiency impairs TNF receptor complex I formation and LUBAC recruitment, and promotes the formation of the cytosolic complex II inducing epithelial cell death. Finally, we show that OTULIN deficiency in IECs increases susceptibility to Salmonella infection, further confirming the importance of OTULIN for intestinal barrier integrity. Together, these results identify OTULIN as a major anti-apoptotic protein in the intestinal epithelium and provide mechanistic insights into how OTULIN deficiency drives gastrointestinal inflammation in ORAS patients.
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Enfermedades Inflamatorias del Intestino , Mucosa Intestinal , Animales , Humanos , Ratones , Apoptosis , Muerte Celular , InflamaciónRESUMEN
OBJECTIVE: ⢠To establish its current status, this study reviews the literature, and reports developments in robotic-assisted partial nephrectomy (RPN), highlighting results from various studies that investigate the oncological and functional efficacy of RPN. Partial nephrectomy has become the standard therapy for the management of small renal masses. In an effort to overcome the perioperative morbidity associated with an open approach, and the extended warm ischaemia times associated with a laparoscopic approach, robotic platforms have been introduced. PATIENTS AND METHODS: ⢠A search of Medline, EMBASE and Cochrane library databases was completed in July 2010 and used to identify pertinent original articles, editorials, comments and reviews, using the search term 'partial nephrectomy'. Links to related references were surveyed, and all articles finally included were based on relevance and importance of content, as determined by the authors. RESULTS: ⢠The robotic platform may offer the solution to bridge the gap between open and laparoscopic approaches, achieving warm ischaemia times that consistently average 20 minutes, and providing similar oncological and functional results via a shorter learning curve. It offers cosmesis and convalescence equivalent to that from laparoscopic partial nephrectomy, but with potentially fewer postoperative complications. CONCLUSION: ⢠In terms of oncological and functional outcomes, the early experiences of RPN in selected series of patients appear at least equivalent to open and laparoscopic partial nephrectomy series. Randomized comparisons between the approaches are lacking, as are longer-term follow-up data for the robotic technique and formal cost analysis; these will be necessary before RPN can replace open partial nephrectomy as the new standard for the management of small renal masses. Trends continue to emerge that highlight the advantage of using the robotic platform to achieve a minimally invasive approach for partial nephrectomy, and with time and increasing expertise, this may become further apparent.
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Nefrectomía/métodos , Robótica , Predicción , Humanos , Laparoscopía , Procedimientos Quirúrgicos Mínimamente Invasivos , Nefrectomía/tendencias , Isquemia TibiaRESUMEN
How do democratic states induce citizens to comply with government directives during times of acute crisis? Focusing on the onset of the Covid-19 pandemic in France, I argue that the tools states use to activate adherence to public health advice have predictable and variable effects on citizens' willingness to change their routine private behaviours, both because of variation in their levels of restrictiveness but also because of differences in people's political motivations to comply with them. Using data collected in March 2020, I show that people's reports of changes in their behavioural routines are affected by the signals governments send, how they send them and the level of enforcement. I find that a nationally televised speech by President Macron calling for cooperative behaviour and announcing new restrictions elevated people's willingness to comply. Moreover, while co-partisanship with the incumbent government increased compliance reports before the President's primetime television address, presidential approval boosted reports of compliance after.
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Water quality from forested landscapes tends to be very high but can deteriorate during and after silvicultural activities. Practices such as forest harvesting, site preparation, road construction/use, and stream crossings have been shown to contribute sediment, nutrients, and other pollutants to adjacent streams. Although advances in forest management accompanied with Best Management Practices (BMPs) have been very effective at reducing water quality impacts from forest operations, projected increases in demand for forest products may result in unintended environmental degradation. Through a review of the pertinent literature, we identified several research gaps related to water yield, aquatic habitat, sediment source and delivery, and BMP effectiveness that should be addressed for streams in the United States to better understand and address the environmental ramifications of current and future levels of timber production. We explored the current understanding of these topics based on relevant literature and the possible implications of increased demand for forest products in the United States.
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Monitoreo del Ambiente/métodos , Agricultura Forestal/métodos , Sedimentos Geológicos/análisis , Ríos/química , Contaminantes del Agua/análisis , Conservación de los Recursos Naturales/métodos , Agricultura Forestal/estadística & datos numéricos , Sedimentos Geológicos/química , Modelos Teóricos , Investigación , Transportes , Estados Unidos , Contaminantes del Agua/química , Contaminación del Agua/estadística & datos numéricos , Abastecimiento de Agua/análisis , Abastecimiento de Agua/estadística & datos numéricosRESUMEN
For decades, researchers have examined people's beliefs across countries and over time using national samples of citizens. Yet, in an era when economies, societies, and policymaking have become increasingly interconnected, nation-states may no longer be the only or most relevant units of analysis for studying public opinion. To examine what people think about politics on a global scale, we develop tools for measuring public opinion that allow us to transcend national and regional boundaries. Starting with the world as the unit of analysis and humans as the relevant population, we measure and then explore patterns and trends in human preferences for democratic government and political leaders with the help of surveys collected around the world since 1994.
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Sequence analysis of the X-linked iduronate-2-sulfatase (IDS) gene in two Hunter syndrome patients revealed a lack of concordance between IDS genomic DNA and cDNA. These individuals were found to be hemizygous respectively for a nonsense mutation [c.22C>T;p.R8X] and a frameshift micro-insertion [c.10insT;p.P4Sfs] in their genomic DNA. However, both wild-type and mutant IDS sequences were evident upon cDNA analysis. Similar discrepant results were also obtained in a third unrelated patient carrying the same p.R8X mutation. Since both p.R8X mutations were inherited from carrier mothers, somatic mosaicism could be excluded. Although the presence of wild-type IDSmRNA-transcripts was confirmed in all three patients by restriction enzyme digestion, clone sequencing, pyrosequencing and single nucleotide primer extension (SNuPE), no wild-type IDS genomic sequence was detectable. The relative abundance of wild-type and mutation-bearing IDS-transcripts in different tissues was quantified by SNuPE. Although IDS transcript levels, as measured by real-time PCR, were reduced (51-71% normal) in these patients, some wild-type IDS protein was detectable by western blotting. Various possible explanations for these unprecedented findings (e.g. accidental contamination, artefactual in vitro nucleotide misincorporation, malsegregation of an extra maternal X-chromosome) were explored and experimentally excluded. PCR-based discriminant assay and segregation analysis of a linked IDS polymorphism (rs1141608) also served to exclude the presence of IDS cDNA derived from the maternal wild-type chromosome. Although it remains to be formally demonstrated by direct experimentation, the intriguing possibility arises that we have observed the in vivo correction of heritable gene lesions at the RNA level operating via a correction mechanism akin to RNA-editing. (c) 2010 Wiley-Liss, Inc.
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Glicoproteínas/genética , Mucopolisacaridosis II/enzimología , Mucopolisacaridosis II/genética , Mutación/genética , Adolescente , Adulto , Secuencia de Bases , Western Blotting , Niño , Preescolar , Análisis Mutacional de ADN , ADN Complementario/genética , Femenino , Regulación Enzimológica de la Expresión Génica , Humanos , Masculino , Datos de Secuencia Molecular , Proteínas Mutantes/genética , Linaje , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Cromosomas Sexuales/genética , Adulto JovenRESUMEN
Regulated macrophage death has emerged as an important mechanism to defend against intracellular pathogens. However, the importance and consequences of macrophage death during bacterial infection are poorly resolved. This is especially true for the recently described RIPK3-dependent lytic cell death, termed necroptosis. Salmonella enterica serovar Typhimurium is an intracellular pathogen that precisely regulates virulence expression within macrophages to evade and manipulate immune responses, which is a key factor in its ability to cause severe systemic infections. We combined genetic and pharmacological approaches to examine the importance of RIPK3 for S. Typhimurium-induced macrophage death using conditions that recapitulate bacterial gene expression during systemic infection in vivo Our findings indicate that noninvasive S. Typhimurium does not naturally induce macrophage necroptosis but does so in the presence of pan-caspase inhibition. Moreover, our data suggest that RIPK3 induction (following caspase inhibition) does not impact host survival following S. Typhimurium infection, which differs from previous findings based on inert lipopolysaccharide (LPS) injections. Finally, although necroptosis is typically characterized as highly inflammatory, our data suggest that RIPK3 skews the peritoneal myeloid population away from an inflammatory profile to that of a classically noninflammatory profile. Collectively, these data improve our understanding of S. Typhimurium-macrophage interactions, highlight the possibility that purified bacterial components may not accurately recapitulate the complexity of host-pathogen interactions, and reveal a potential and unexpected role for RIPK3 in resolving inflammation.IMPORTANCE Macrophages employ multiple strategies to limit pathogen infection. For example, macrophages may undergo regulated cell death, including RIPK3-dependent necroptosis, as a means of combatting intracellular bacterial pathogens. However, bacteria have evolved mechanisms to evade or exploit immune responses. Salmonella is an intracellular pathogen that avoids and manipulates immune detection within macrophages. We examined the contribution of RIPK3 to Salmonella-induced macrophage death. Our findings indicate that noninvasive Salmonella does not naturally induce necroptosis, but it does so when caspases are inhibited. Moreover, RIPK3 induction (following caspase inhibition) does not impact host survival following Salmonella systemic infection. Finally, our data show that RIPK3 induction results in recruitment of low-inflammatory myeloid cells, which was unexpected, as necroptosis is typically described as highly inflammatory. Collectively, these data improve our understanding of pathogen-macrophage interactions, including outcomes of regulated cell death during infection in vivo, and reveal a potential new role for RIPK3 in resolving inflammation.