Lung gene expression analysis of WT, Nlrp3-, Asc-deficient mice in Streptococcus pneumoniae D39 and ATCC6303 infection
ABSTRACT: Streptococcus (S.) pneumoniae is the most frequently isolated causative pathogen community-acquired pneumonia, a leading cause of mortality worldwide. We investigated the role of the inflammasome sensor NLRP3 and the inflammasome adapter ASC during S. pneumoniae pneumonia. Detailed analysis of the early inflammatory response in the lung by whole genome transcriptional profiling, we identified several mediators that were differentially expressed between Nlrp3-/- and Asc-/ - mice. WT, Nlrp3- and Asc-deficient mice were intranasally inocculated with Streptococcus pneumoniae D39 and ATCC6303 both at high and low dose. Lung homogenates were harvested and gene expression profiling was performed.
Project description:Inflammasomes are multiprotein platforms of caspase-1 activation. The NLRP3 inflammasome is composed of NLRP3, ASC, and procaspase-1. This inflammasome is activated by various endogenous and exogenous stimuli, including pneumococci, and protects from a variety of microbial pathogens. In the present study, we examined the role of NLRP3 inflammasome components in gene expression in the lung during pneumococcal pneumina. Overall design: Gene expression was measured in the lung of WT, Casp1-/-, Asc-/-, and Nlrp3-/- mice 24 h after intranasal infection with Streptococcus pneuminiae.
Project description:The adaptor protein ASC contributes to innate immunity through the assembly of caspase-1-activating inflammasome complexes. We demonstrate that ASC plays an inflammasome-independent cell-intrinsic role in adaptive immune cells. Asc-/- mice displayed defective antigen presentation by dendritic cells and lymphocyte migration due to impaired Rac-mediated actin polymerization. Genome-wide analysis showed that ASC, but not Nlrp3 or caspase-1, controls mRNA stability and expression of DOCK2, a guanine nucleotide exchange factor that mediates Rac-dependent signaling in immune cells. DOCK2-deficient dendritic cells showed similar defective antigen uptake as Asc-/- cells. Ectopic expression of DOCK2 in ASC-deficient cells restored Rac-mediated actin polymerization, antigen uptake and chemotaxis. Thus, ASC shapes adaptive immunity independently of inflammasomes by modulating DOCK2-dependent Rac activation and F-actin polymerization in dendritic cells and lymphocytes. Three replicates of naïve WT and three replicates of Asc-/- bone marrow derived dendritic cells were analyzed on the Affymetrix HT MG-430 PM plate array.
Project description:NLRP3 inflammasome assembles in response to stress or danger signals and leads to unconventional secretion of proinflammatory IL-1. FADD is an NLRP3 inflammasome component. Here we found that classical NLRP3 inflammasome activation in human monocytes/macrophages induced FADD secretion, which required potassium efflux, functional NLRP3 sensor, ASC adaptor and caspase-1 scaffold molecule. FADD is a leaderless protein unconventionally secreted through plasma membrane-derived microvesicles. Blood-derived monocytes from rheumatoid arthritis (RA) patients secreted more FADD following NLRP3 inflammasome activation than those from healthy donors, and we found increased levels of FADD in the sera (ESPOIR cohort) and synovial fluids from RA patients. Levels of synovial FADD correlated with the inflammatory status of the joint. These data reveal that FADD secretion occurs during inflammatory disease in vivo.
Project description:This experiment was performed to analyze the contribution of NLRP3 inflammasome activation to age-related changes in hippocampal RNA. The hypothesis was that decreased inflammasome activation would reduce hippocampal inflammation. Results indicate that inflammasome knockout animals are protected from age-related changes in hippocampal gene expression Gene expression profiles of young (1 month) and old (21-23 month) wild type, CIAS -/- and ASC -/- mouse hippocampal tissue were compared. Total mRNA was extracted using Trizol.
Project description:The adaptor protein ASC is known to facilitate caspase-1 activation essential for innate host immunity via the formation of the inflammasome complex - a multi-protein structure responsible for processing IL-1beta and IL-18 to their active moieties. Here we demonstrate that ASC-deficient CD8+ T cells fail to induce graft-versus-host disease (GVHD) and have impaired capacity for graft rejection and graft-versus-leukemia (GVL) activity. These effects are the result of an inability to differentiate into fully cytolytic, granzyme B-expressing effector cells, with a developmental bias instead towards CD127+KLRG1- memory CD8+ T cells. These alterations in differentiation are inflammasome-independent, since GVHD lethality and CTL differentiation are not altered in recipients of caspase-1-deficient T cells. We demonstrate that ASC binds to T-bet in CD8+ T and in the absence of ASC, the binding of T-bet to the granzyme B promoter is impaired. Thus, the inhibition of ASC represents an attractive therapeutic target to manipulate transplant outcomes. Single colour, Illumina MouseRef-8 v2.0 Beadarrays.
Project description:Transcriptional effects in liver, lung and blood samples from mice after intratracheal challenge with either Streptococcus pneumoniae serotype 19 (lobar-pneumonia) or serotype 2 (sepsis) were monitored after 6 and 24 hours and compared to sham (vehicle control). We gratefully acknowledge the BMBF grant within the “Promoting global research excellence in severe sepsis” (PROGRESS) study (01KI07111). Three tissues x two serotypes x two time resolved treatment groups x four replicates, three tissues x Sham Control x three replicates.
Project description:Inflammation plays a key role in the pathogenesis of obesity. Chronic overfeeding leads to macrophage infiltration in the adipose tissue, resulting in pro-inflammatory cytokine production. Both microbial and endogenous danger signals trigger assembly of the intracellular innate immune sensor Nlrp3 [NLR family, pyrin domain containing 3] resulting in caspase-1 activation and production of pro-inflammatory cytokines interleukin (IL)-1beta and IL-18. Here, we showed that mice deficient in Nlrp3, ASC [apoptosis-associated speck-like protein containing a CARD; a.k.a PYCARD (PYD and CARD domain containing)] and caspase-1 were resistant to the development of high fat diet-induced obesity, which correlated with protection from obesity-induced insulin resistance. Detailed metabolic and molecular phenotyping demonstrated that the inflammasome controls energy expenditure and adipogenic gene expression during chronic overfeeding. These findings reveal a critical function of the inflammasome in obesity and insulin resistance and suggest inhibition of the inflammasome as a potential therapeutic strategy. Keywords: Expression profiling by array Wild-type (WT), ASC-null and Casp1-null mice were subjected to high fat diet feeding for 16 weeks. After the diet intervention period, the animals were killed and epididymal white adipose tissue was removed. Total RNA was isolated and subjected to gene expression profiling.
Project description:Inflammation plays a key role in the pathogenesis of obesity. Chronic overfeeding leads to macrophage infiltration in the adipose tissue, resulting in pro-inflammatory cytokine production. Both microbial and endogenous danger signals trigger assembly of the intracellular innate immune sensor Nlrp3 [NLR family, pyrin domain containing 3] resulting in caspase-1 activation and production of pro-inflammatory cytokines interleukin (IL)-1beta and IL-18. Here, we showed that mice deficient in Nlrp3, ASC [apoptosis-associated speck-like protein containing a CARD; a.k.a PYCARD (PYD and CARD domain containing)] and caspase-1 were resistant to the development of high fat diet-induced obesity, which correlated with protection from obesity-induced insulin resistance. Detailed metabolic and molecular phenotyping demonstrated that the inflammasome controls energy expenditure and adipogenic gene expression during chronic overfeeding. These findings reveal a critical function of the inflammasome in obesity and insulin resistance and suggest inhibition of the inflammasome as a potential therapeutic strategy. Keywords: Expression profiling by array Overall design: Wild-type (WT), ASC-null and Casp1-null mice were subjected to high fat diet feeding for 16 weeks. After the diet intervention period, the animals were killed and epididymal white adipose tissue was removed. Total RNA was isolated and subjected to gene expression profiling.
Project description:Inflammasomes are multi-protein complexes that control the production of pro-inflammatory cytokines such as IL-1beta. Inflammasomes play an important role in the control of immunity to tumors and infections, and also in autoimmune diseases, but the mechanisms controlling the activation of human inflammasomes are largely unknown. We found that human activated CD4+CD45RO+ memory T-cells specifically suppress P2X7R-mediated NLRP3 inflammasome activation, without affecting P2X7R-independent NLRP3 or NLRP1 inflammasome activation. The concomitant increase in pro-IL-1β production induced by activated memory T-cells concealed this effect. Priming with IFNβ decreased pro-IL-1β production in addition to NLRP3 inflammasome inhibition and thus unmasked the inhibitory effect on NLRP3 inflammasome activation. IFNβ did not suppress NLRP3 inflammasome activation by acting directly on monocytes. The inhibition of pro-IL-1β production and suppression of NLRP3 inflammasome activation by IFNβ-primed human CD4+CD45RO+ memory T-cells is partly mediated by soluble FasL and is associated with down-regulated P2X7R mRNA expression and reduced response to ATP in monocytes. CD4+CD45RO+ memory T-cells from multiple sclerosis (MS) patients showed a reduced ability to suppress NLRP3 inflammasome activation, however their suppressive ability was recovered following in vivo treatment with IFNβ. Thus, our data demonstrate that human P2X7R-mediated NLRP3 inflammasome activation is regulated by activated CD4+CD45RO+ memory T cells, and provide new information on the mechanisms mediating the therapeutic effects of IFNβ in MS. Memory T-cells were cultured in the presence of monocytes with and without Interferon-beta, resorted and expression profile was determined
Project description:Inflammasome, activated by pathogen-derived and host-derived danger signals, constitutes a multimolecular signaling complex that serves as a platform for caspase-1 (CASP1) activation and interleukin-1beta (IL1B) maturation. The activation of NLRP3 inflammasome requires two-step signals. The first “priming” signal (Signal 1) enhances gene expression of inflammasome components. The second “activation” signal (Signal 2) promotes the assembly of inflammasome components. Deregulated activation of NLRP3 inflammasome contributes to the pathological processes of Alzheimer’s disease (AD) and multiple sclerosis (MS). However, at present, the precise mechanism regulating NLRP3 inflammasome activation and deactivation remains largely unknown. By genome-wide gene expression profiling, we studied the molecular network of NLRP3 inflammasome activation-responsive genes in a human monocyte cell line THP-1 sequentially given two-step signals. We identified the set of 83 NLRP3 inflammasome activation-responsive genes. Among them, we found the NR4A nuclear receptor family NR4A1, NR4A2, and NR4A3, the EGR family EGR1, EGR2, and EGR3, the IkappaB family NFKBIZ, NFKBID, and NFKBIA as a key group of the genes that possibly constitute a negative feedback loop for shutting down inflammation following NLRP3 inflammasome activation. By molecular network analysis, we identified a complex network of NLRP3 inflammasome activation-responsive genes involved in cellular development and death, and immune and inflammatory responses, where transcription factors AP-1, NR4A, and EGR serve as a hub. Thus, NLRP3 inflammasome activation-responsive genes constitute the molecular network composed of a set of negative feedback regulators for prompt resolution of inflammation. To load the Signal 1 (S1), THP-1 cells were incubated for 3 hours in the culture medium with or without inclusion of 0.2 microgram/ml lipopolysaccharide (LPS). To load the Signal 2 (S2), they were incubated further for 2 hours in the culture medium with inclusion of 10 microM nigericin sodium salt dissolved in ethanol or the equal v/v% concentration of ethanol (vehicle), followed by processing for microarray analysis on Human Gene 1.0 ST Array (Affymetrix).