Systemic infections with Gram-negative bacteria are characterized by high mortality rates due to the "sepsis syndrome," a widespread and uncontrolled inflammatory response. Though it is well recognized that the immune response during Gram-negative bacterial infection is initiated after the recognition of endotoxin by Toll-like receptor 4, the molecular mechanisms underlying the detrimental inflammatory response during Gram-negative bacteremia remain poorly defined. Here, we identify a TRIF pathway that licenses NLRP3 inflammasome activation by all Gram-negative bacteria. By engaging TRIF, Gram-negative bacteria activate caspase-11. TRIF activates caspase-11 via type I IFN signaling, an event that is both necessary and sufficient for caspase-11 induction and autoactivation. Caspase-11 subsequently synergizes with the assembled NLRP3 inflammasome to regulate caspase-1 activation and leads to caspase-1-independent cell death. These events occur specifically during infection with Gram-negative, but not Gram-positive, bacteria. The identification of TRIF as a regulator of caspase-11 underscores the importance of TLRs as master regulators of inflammasomes during Gram-negative bacterial infection.
NLRP3 inflammasome activation in macrophage cell lines by prion protein fibrils as the source of IL-1beta and neuronal toxicity
Prion diseases are fatal transmissible neurodegenerative diseases, characterized by aggregation of the pathological form of prion protein, spongiform degeneration, and neuronal loss, and activation of astrocytes and microglia. Microglia can clear prion plaques, but on the other hand cause neuronal death via release of neurotoxic species. Elevated expression of the proinflammatory cytokine IL-1beta has been observed in brains affected by several prion diseases, and IL-1R-deficiency significantly prolonged the onset of the neurodegeneration in mice. We show that microglial cells stimulated by prion protein (PrP) fibrils induced neuronal toxicity. Microglia and macrophages release IL-1beta upon stimulation by PrP fibrils, which depends on the NLRP3 inflammasome. Activation of NLRP3 inflammasome by PrP fibrils requires depletion of intracellular K(+), and requires phagocytosis of PrP fibrils and consecutive lysosome destabilization. Among the well-defined molecular forms of PrP, the strongest NLRP3 activation was observed by fibrils, followed by aggregates, while neither native monomeric nor oligomeric PrP were able to activate the NLRP3 inflammasome. Our results together with previous studies on IL-1R-deficient mice suggest the IL-1 signaling pathway as the perspective target for the therapy of prion disease.
5,6-Dimethylxanthenone-4-acetic acid (DMXAA) activates stimulator of interferon gene (STING)-dependent innate immune pathways and is regulated by mitochondrial membrane potential
The chemotherapeutic agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) is a potent inducer of type I IFNs and other cytokines. This ability is essential for its chemotherapeutic benefit in a mouse cancer model and suggests that it might also be useful as an antiviral agent. However, the mechanism underlying DMXAA-induced type I IFNs, including the host proteins involved, remains unclear. Recently, it was reported that the antioxidant N-acetylcysteine (NAC) decreased DMXAA-induced TNF-alpha and IL-6, suggesting that oxidative stress may play a role. The goal of this study was to identify host proteins involved in DMXAA-dependent signaling and determine how antioxidants modulate this response. We found that expression of IFN-beta in response to DMXAA in mouse macrophages requires the mitochondrial and endoplasmic reticulum resident protein STING. Addition of the antioxidant diphenylene iodonium (DPI) diminished DMXAA-induced IFN-beta, but this decrease was independent of both the NADPH oxidase, Nox2, and de novo generation of reactive oxygen species. Additionally, IFN-beta up-regulation by DMXAA was inhibited by agents that target the mitochondrial electron transport chain and, conversely, loss of mitochondrial membrane potential correlated with diminished innate immune signaling in response to DMXAA. Up-regulation of Ifnb1 gene expression mediated by cyclic dinucleotides was also impaired by DPI, whereas up-regulation of Ifnb1 mRNA due to cytosolic double-stranded DNA was not. Although both stimuli signal through STING, cyclic dinucleotides interact directly with STING, suggesting that recognition of DMXAA by STING may also be mediated by direct interaction.
Cutting Edge: FAS (CD95) mediates noncanonical IL-1beta and IL-18 maturation via caspase-8 in an RIP3-independent manner
Fas, a TNF family receptor, is activated by the membrane protein Fas ligand expressed on various immune cells. Fas signaling triggers apoptosis and induces inflammatory cytokine production. Among the Fas-induced cytokines, the IL-1beta family cytokines require proteolysis to gain biological activity. Inflammasomes, which respond to pathogens and danger signals, cleave IL-1beta cytokines via caspase-1. However, the mechanisms by which Fas regulates IL-1beta activation remain unresolved. In this article, we demonstrate that macrophages exposed to TLR ligands upregulate Fas, which renders them responsive to receptor engagement by Fas ligand. Fas signaling activates caspase-8 in macrophages and dendritic cells, leading to the maturation of IL-1beta and IL-18 independently of inflammasomes or RIP3. Hence, Fas controls a novel noncanonical IL-1beta activation pathway in myeloid cells, which could play an essential role in inflammatory processes, tumor surveillance, and control of infectious diseases.
This article is based upon a paper delivered by Anne Beales to the International Initiative for Mental Health Leadership, IIMHL, Conference in Killarney, Ireland, May 2010, and developed by the Interrelate group: Daniel Fisher, US, Shaun McNeil, Scotland, Jenny Speed, Australia, Paddy MacGowan, Ireland, Gary Platz, New Zealand, and Joan Edwards-Karmazyn, Canada.
MISSION DIRECT VET (Maintaining Independence and Sobriety through Systems Integration, Outreach, and Networking Diversion & Recovery for Traumatized Veterans, “MDV”) is a study funded by a grant from SAMHSA to the Massachusetts Department of Mental Health (DMH) being conducted by UMass Medical School, UMass Boston, the Veterans Administration, the DMH, and other state agencies. This court-based diversion program serves Massachusetts veterans with trauma-related mental health and substance use problems.
Trends in the use of antiepileptic drugs among pregnant women in the US, 2001-2007: a medication exposure in pregnancy risk evaluation program study
BACKGROUND: Little is known about the extent of antiepileptic drug (AED) use in pregnancy, particularly for newer agents. Our objective was to assess whether AED use has increased among pregnant women in the US, 2001-2007.
METHODS: We analysed data from the Medication Exposure in Pregnancy Risk Evaluation Program (MEPREP) database, 1 January 2001 to 31 December 2007. We identified liveborn deliveries among women, aged 15-45 years on delivery date, who were members of MEPREP health plans (n=585615 deliveries). Pregnancy exposure to AEDs, determined through outpatient pharmacy dispensing files. Older AEDs were available for clinical use before 1993; other agents were considered newer AEDs. Information on sociodemographic and medical/reproductive factors was obtained from linked birth certificate files. Maternal diagnoses were identified based on ICD-9 codes.
RESULTS: Prevalence of AED use during pregnancy increased between 2001 (15.7 per 1000 deliveries) and 2007 (21.9 per 1000 deliveries), driven primarily by a fivefold increase in the use of newer AEDs. Thirteen per cent of AED-exposed deliveries involved a combination of two or more AEDs. Psychiatric disorders were the most prevalent diagnoses, followed by epileptic and pain disorders, among AED users regardless of AED type, year of conception or gestational period.
CONCLUSIONS: AED use during pregnancy increased between 2001 and 2007, driven by a fivefold increase in the use of newer AEDs. Nearly one in eight AED-exposed deliveries involved the concomitant use of more than one AED. Additional investigations of the reproductive safety of newer AEDs may be needed.
OBJECTIVE: To describe the prevalence, trends, and patterns in use of antidiabetic medications to treat hyperglycemia and insulin resistance before and during pregnancy in a large U.S. cohort of insured pregnant women.
METHODS: Pregnancies resulting in live births were identified (N=437,950) from 2001 to 2007 among 372,543 females 12-50 years of age at delivery from 10 health maintenance organizations participating in the Medication Exposure in Pregnancy Risk Evaluation Program. Information for these descriptive analyses, including all antidiabetic medications dispensed during this period, was extracted from electronic health records and newborn birth certificates.
RESULTS: A little more than 1% (1.21%) of deliveries were to women dispensed antidiabetic medication in the 120 days before pregnancy. Use of antidiabetic medications before pregnancy increased from 0.66% of deliveries in 2001 to 1.66% of deliveries in 2007 (P<.001) because of an increase in metformin use. Most women using metformin before pregnancy had a diagnosis code for polycystic ovaries or female infertility (67.2%), whereas only 13.6% had a diagnosis code for diabetes. The use of antidiabetic medications during the second or third trimester of pregnancy increased from 2.8% of deliveries in 2001 to 3.6% in 2007 (P<.001). Approximately two thirds (68%) of women using metformin before pregnancy did not use any antidiabetic medications during pregnancy.
CONCLUSIONS: Antidiabetic medication use before and during pregnancy increased from 2001 to 2007, possibly because of increasing prevalence of gestational diabetes mellitus, type 1 and type 2 diabetes, and other conditions associated with insulin resistance.
LEVEL OF EVIDENCE: III.
Characteristics associated with anti-osteoporosis medication use: data from the Global Longitudinal Study of Osteoporosis in Women (GLOW) USA cohort
INTRODUCTION: Many women at risk of fracture do not receive anti-osteoporosis medication (AOM), while others may be receiving unnecessary treatment.
PURPOSE: To examine the characteristics associated with AOM use among women at low and high risks of fracture.
METHODS: The Global Longitudinal Study of Osteoporosis in Women (GLOW) is a prospective cohort study in which data were collected, via self-administered questionnaires, from 60,393 non-institutionalized women aged >/= 55 years in 10 countries between October 1, 2006 and April 30, 2008. This is a cross-sectional analysis of baseline USA data, in which women were classified as having low fracture risk (<65 >years; no FRAX risk factors) or high fracture risk (>/=65 years; prior fracture or >/= 2 other FRAX risk factors).
RESULTS: Of 27,957 women, 3013 were at low risk of fracture and 3699 were at high risk. Only 35.7% of high-risk women reported AOM treatment, rising to 39.5% for those with self-reported osteopenia and 65.4% for those with self-reported osteoporosis. Conversely, 13.4% of low-risk women reported AOM, rising to 28.7% for osteopenia and 62.4% for osteoporosis. Characteristics associated with significantly higher AOM treatment rates among low- and high-risk women were: osteoporosis (odds ratios 75.3 and 18.1, respectively), osteopenia (17.9 and 6.3), concern about osteoporosis (2.0 and 1.8), higher perceived risk of fracture (2.3 and 1.6), and higher vitality score (1.7 and 1.6).
CONCLUSION: Use of AOM is frequently inconsistent with published guidelines in both high- and low-risk women. Characteristics other than FRAX fracture risk appear to influence this use, particularly the presence of self-reported osteoporosis.
Influence of 23 coronary artery disease variants on recurrent myocardial infarction or cardiac death: the GRACE Genetics Study
Aims: A pooled analysis of 14 genome-wide association studies revealed 23 susceptibility loci for coronary artery disease (CAD), thereby providing the most comprehensive genetic blueprint of CAD susceptibility. Here, we evaluated whether these 23 loci also predispose to recurrent myocardial infarction (MI) or cardiac death following an acute coronary syndrome (ACS).
Methods and results: A total of 2099 ACS patients enrolled in the Global Registry of Acute Coronary Events (GRACE) UK-Belgian study were prospectively followed for a median of 5 years (1668 days). C-allele carriers of the rs579459 variant, which is located upstream of the ABO gene and correlates with blood group A, were independently associated with recurrent MI [multivariable-adjusted hazard ratio (HR) 2.25, CI = 1.37-3.71; P = 0.001] and with recurrent MI or cardiac death [multivariable-adjusted (HR) 1.80, CI = 1.09-2.95; P = 0.021] within 5 years after an index ACS. The association of rs579459 was replicated in 1250 Polish patients with 6 months follow-up after an index ACS [multivariable-adjusted (HR) 2.70, CI = 1.26-5.82; P = 0.011 for recurrent MI]. Addition of rs579459 to a prediction model of 17 clinical risk factors improved risk classification for recurrent MI or cardiac death at 6 months as calculated by the integrated discrimination improvement method (P = 0.037), but not by C-statistics (P = 0.096).
Conclusion: In this observational study, rs579459 was independently associated with adverse cardiac outcome after ACS. A weak improvement in clinical risk prediction was also observed, suggesting that rs579459 should be further tested as a potentially relevant contributor to risk prediction models for adverse outcome following ACS.