Project description:Because the immune regulation in survivor after sepsis (an immune dysregulation from severe infection) might be applied for treatment, survivors and moribund mice after cecal liga-tion and puncture (CLP) and in vitro experiments on macrophages were explored. Most of the parameters in survivors (5-days post-CLP) were normalized, except for the slightly increase in alanine transaminase, IL-10, lipopolysaccharide (LPS) and gut leakage (FITC-dextran assay), with the enhanced adaptive immunity; serum immunoglobulin (using serum protein electrophoresis) and activated immune cells in spleens (flow cytometry analysis). Then, a clue to surviving sepsis may be effective innate immunity regulation by adaptive immune responses. Indeed, soluble heat aggregated immunoglobulin (sHA-Ig, a representative of immune complex) in LPS-activated macrophages reduced supernatant cytokines and down-regulated proteins in sev-eral processes (using proteomic analysis). As a proof of concept, intravenous immunoglobulin (IVIG) attenuated sepsis severity in CLP mice as evaluated by serum creatinine, ALT, serum cy-tokines, spleen apoptosis (24 h post-CLP) and 48 h survival analysis. In conclusion, immuno-globulin may play a role in sepsis immune hyper-responsiveness. Despite the debate over IVIG's use in sepsis, adequate selection criteria for sepsis patients who may benefit the most from IVIG could lead to an increase use of this clinically viable treatment.
Project description:Biofilms are a communal of one or several kinds of microorganisms that growing on of both non-living and biotic surfaces by the production of multi-layers high-abundance extracellular matrix (ECM) to survive in the harsh environments (1-4). Biofilms consist of 85% (by volume) of matrix materials and 15% microbial cells (5). Biofilm ECM, consists of proteins, polysaccharides and/or extracellular DNAs, is important for biofilm integrity that increases environmental adaptability and induces antimicrobial resistance (6-7). Surface-adherent (sessile) bacteria in biofilms are more difficult to eradicate as minimum inhibitory concentrations (MICs) of antibiotics against bacterial biofilms is 100-1000 folds higher than the free living (planktonic) form that resulting in recurrent infections (8). Biofilms also possibly form nidus at the surface for the attachment of other pathogens lead to biofilms of multiple bacteria or multi-organisms (9ref). The communication, among organisms within biofilm, controls density of cell population refers to as “quorum sensing” (10) and different combinations of organisms in biofilms with either multiple bacteria or multi-species might induce different biofilm properties. While catheter-related colonization of Gram-positive bacteria from skin microbiota such as Streptococcus spp. and Staphylococcus spp. is common, biofilms in the inner lumen of catheter consist of both Gram-positive and Gram-negative bacteria. Because i) translocation of gut microbiota (eg. Enterococcus spp., Gram-negative bacteria and Candida albicans) into blood circulation during sepsis is one of the common causes of severe sepsis , ii) mixed systemic infection between bacteria and Candida spp. is even more severe than the infection by each organism in separation and iii) biofilms could be formed during bacteremia and fungemia, the biofilms from mixed species between bacteria and Candida spp. during sepsis is possible. In addition, central venous catheter-related candidiasis is common in intensive care units (ICU) patients refer to as “Candida catheter-related bloodstream infection (CRCBSI)”. Moreover, synergistic interaction between Candida albicans and several Gram-negative bacteria such as Escherichia coli (in peritonitis), Pseudomonas aeruginosa (in cystic fibrosis and ventilation associated pneumonia) and Acinetobacter baumannii (in ventilation associated pneumonia) has been mentioned. Hence, the collaboration between bacteria and Candida spp. might affect biofilm production as C. albicans in coexistence with the sessile microbes possibly enhance biofilms production that is detectable by crystal violet color (16,7). It is interesting to note that C. albicans are normal microbiota in human intestine and gut-translocation from intestine into blood circulation during severe sepsis (gut leakage) is demonstrated. Furthermore, both Gram-negative bacteria and C. albicans are the most and the second most predominant intestinal human microbiota, respectively, in which the natural interactions between these organisms is possible. Accordingly, catheter-related bacteremia is common among patients in ICU. Gut translocation of Candida spp. during sepsis, due to gut leakage, might induce the collaboration between bacteria and fungi results in persistent infection (20-21Chen L, 2011, 66//Wu H, 2015, 1, IJOS). Although the understanding in the interaction between organisms in biofilms should be beneficial for eradication strategies, the data of biofilms from the combination between gut-derived bacteria and fungi is still limited. As such, production of exo-polymers for biofilm-forming is a pathogenic virulent factor because biofilms is one of the important defend-mechanisms against host immune responses and antibiotics. Because i) antibiotic resistance caused by biofilm is a current serious medical problem , ii) the eradication of both bacterial and fungal biofilms is difficult and iii) antimicrobial treatment without biofilms-removal resulting in recurrent or persistent infection (23ref), biofilm prevention agent is needed (2410). Here, we explored i) the interaction between Gram-negative bacteria and C. albicans, in vitro, ii) macrophage responses against biofilm components, iii) biofilms in catheter-insertion mouse model and an evaluation on an interesting anti-biofilm.
Project description:Intestinal barrier leakage constitutes a potential therapeutic target for many inflammatory diseases and represents a disease progression marker during chronic viral infections. The causes of altered gut barrier remain, however, mostly unknown. By using murine infection with lymphocytic choriomeningitis virus we demonstrated that, in contrast to an acute viral strain, a persistent viral isolate led to long-term viral replication in hematopoietic and mesenchymal, but not epithelial (IEC), cells in the intestine. Viral persistence drove sustained intestinal epithelial barrier leakage, which was characterized by increased paracellular flux of small molecules and was associated with enhanced colitis susceptibility. IFN-I signaling caused tight junction dysregulation in IEC, promoted gut microbiome shifts and enhanced intestinal CD8 T cell responses. Notably, both IFN-I receptor blockade and CD8 T cell depletion prevented infection-induced barrier leakage. Our study demonstrated that infection with a virus that persistently replicated in intestinal mucosa increased epithelial barrier permeability, and revealed IFN-I and CD8 T cells as causative factors of intestinal leakage during chronic infections.
Project description:Sepsis is an uncontrolled, systemic response to infection with life-threatening consequences. Our understanding of the pathogenesis of sepsis across organs of the body is rudimentary. Here, using mouse models of sepsis, we generate a dynamic, organism-wide map of the pathogenesis of the disease, revealing the spatiotemporal patterns of well-known and previously unrecognized effects of sepsis on the body. By combining functional perturbations with organism-wide profiling, we discover two interorgan mechanisms that are key to the pathophysiology of sepsis. First, we find that a hierarchical cytokine circuit arising from the pairwise effects of TNF plus IL-18, IFN-γ, or IL-1β suffices to explain a large fraction of the molecular effects of sepsis on the body. Moreover, the effects of these three cytokine pairs on the abundance of nearly two hundred cell types across nine organ types recapitulate half of all the cellular effects of sepsis. Second, we uncover an interorgan pathway whereby a gut-derived, secreted phospholipase, Pla2g5, mediates hemolysis in the blood circulation and contributes to multi-organ failure during sepsis. Thus, a simplifying principle in the systemic behavior of the cytokine network and a lipase misdirected from gut to blood provide fundamental insights to help build a unifying mechanistic framework for the pathophysiological effects of sepsis on the organ systems of the body.
Project description:Sepsis is a systemic response to infection with life-threatening consequences such as hemolysis, a predictor of mortality risks for the disease. Here, by measuring organism-wide changes in gene expression, we discovered that the secreted phospholipase PLA2G5 is induced in colon cell types during sepsis. The genetic deletion and antibody blockade of PLA2G5 abrogated the lethal effects of sepsis. PLA2G5 blockade during sepsis led to an increase in splenic red pulp macrophages and iron homeostasis, linking PLA2G5 to red blood cell homeostasis during sepsis. Mechanistically, bloodborne PLA2G5 led to intravascular hemolysis through its lipolytic activity on red blood cell membranes. In humans with sepsis, the plasma level of PLA2G5 was elevated and predictive of disease severity and mortality. We conclude that sepsis corrupts PLA2G5 from the gut into becoming a systemic self-venom which is toxic for host red blood cells.
Project description:Sepsis-induced acute lung injury (ALI), characterized by severe hypoxemia and pulmonary leakage, remains a leading cause of mortality in intensive care units. The exacerbation of ALI during sepsis is largely attributed to uncontrolled inflammatory responses and endothelial dysfunction. Emerging evidences suggest an important role of Z-DNA binding protein 1 (ZBP1) as a sensor in innate immune to drive inflammatory signaling and cell death during infections. However, the role of ZBP1 in sepsis-induced ALI has yet to be defined. We utilized ZBP1 knockout mice and combined single-cell RNA sequencing with experimental validation to investigate ZBP1's roles in the regulation of macrophages and lung endothelial cells during sepsis. We demonstrate that in sepsis, ZBP1 deficiency in macrophages reduces mitochondrial damage and inhibits glycolysis, thereby altering the metabolic status of macrophages. Consequently, this metabolic shift leads to a reduction in the differentiation of macrophages into pro-inflammatory states and decreases macrophage pyroptosis triggered by activation of the NLRP3 inflammasome. These changes significantly weaken the inflammatory signaling pathways between macrophages and endothelial cells, and alleviate endothelial dysfunction and cellular damage. These findings reveal important roles for ZBP1 in mediating multiple pathological processes involved in sepsis-induced ALI by modulating the functional states of macrophages and endothelial cells, thereby highlighting its potential as a promising therapeutic target.
Project description:The vascular endothelial barrier, which supports balanced plasma solute and macromolecule composition, controls hemostasis, and limits leukocyte extravasation at homeostasis, is frequently disrupted in inflammation associated with sepsis and other critical illness. Monoclonal gammopathy-associated idiopathic systemic capillary leak syndrome (ISCLS, Clarkson disease) is a rare and devastating disorder characterized by relapsing-remitting episodes of spontaneous, profound microvascular hyper-permeability. A loss of function (LOF) mutation (G628R) in the mono ADP-ribosyltransferase PARP15, a protein of unknown function that is absent in mice, is associated with ISCLS and correlates with clinical markers of severe vascular leakage. In vascular endothelial cells, PARP15 suppresses cytokine-induced barrier disruption by ADP-ribosylating the scaffold protein JNK-interacting protein 3 (JIP3) and inhibiting p38 MAP kinase activation. Mice expressing human wild type (WT) PARP15 have curtailed inflammation-associated vascular leakage compared to mice expressing PARP15(G628R) in a p38-dependent fashion. Thus, PARP15 is essential for vascular endothelial barrier function under inflammatory stress.
Project description:<p>Emerging evidence that the gut microbiota may contribute in important ways to human health and disease has led us and others to hypothesize that both symbiotic and pathological relationships between gut microbes and their host may be key contributors to obesity and the metabolic complications of obesity. Our "Thrifty Microbiome Hypothesis" poses that gut microbiota play a key role in human energy homeostasis. Specifically, constituents of the gut microbial community may introduce a survival advantage to its host in times of nutrient scarcity, promoting positive energy balance by increasing efficiency of nutrient absorption and improving metabolic efficiency and energy storage. However, in the presence of excess nutrients, fat accretion and obesity may result, and in genetically predisposed individuals, increased fat mass may result in preferential abdominal obesity, ectopic fat deposition (liver, muscle), and metabolic complications of obesity (insulin resistance, hypertension, hyperlipidemia). Furthermore, in the presence of excess nutrients, a pathological transition of the gut microbial community may occur, causing leakage of bacterial products into the intestinal lymphatics and portal circulation, thereby inducing an inflammatory state, further aggravating metabolic syndrome traits and accelerating atherosclerosis. This pathological transition and the extent to which antimicrobial leakage occurs and causes inflammatory and other maladaptive sequelae of obesity may also be influenced by host factors, including genetics. In the proposed study, we will directly test the Thrifty Microbiome Hypothesis by performing detailed genomic and functional assessment of gut microbial communities in intensively phenotyped and genotyped human subjects before and after intentional manipulation of the gut microbiome. To address these hypotheses, five specific aims are proposed: (1) enroll three age- and sex-matched groups from the Old Order Amish: (i) 50 obese subjects (BMI > 30 kg/m2) with metabolic syndrome, (ii) 50 obese subjects (BMI > 30 kg/m2) without metabolic syndrome, and (iii) 50 non-obese subjects (BMI < 25 kg/m2) without metabolic syndrome and characterize the architecture of the gut microbiota from the subjects enrolled in this study by high-throughput sequencing of 16S rRNA genes; (2) characterize the gene content (metagenome) to assess the metabolic potential of the gut microbiota in 75 subjects to determine whether particular genes or pathways are correlated with disease phenotype; (3) characterize the transcriptome in 75 subjects to determine whether differences in gene expression in the gut microbiota are correlated with disease phenotype, (4) determine the effect of manipulation of the gut microbiota with antibiotics on energy homeostasis, inflammation markers, and metabolic syndrome traits in 50 obese subjects with metabolic syndrome and (5) study the relationship between gut microbiota and metabolic and cardiovascular disease traits, weight change, and host genomics in 1,000 Amish already characterized for these traits and in whom 500K Affymetrix SNP chips have already been completed. These studies will provide our deepest understanding to date of the role of gut microbes in terms of 'who's there?', 'what are they doing?', and 'how are they influencing host energy homeostasis, obesity and its metabolic complications? PUBLIC HEALTH RELEVANCE: This study aims to unravel the contribution of the bacteria that normally inhabit the human gastrointestinal tract to the development of obesity, and its more severe metabolic consequences including cardiovascular disease, insulin resistance and Type II diabetes. We will take a multidisciplinary approach to study changes in the structure and function of gut microbial communities in three sets of Old Order Amish patients from Lancaster, Pennsylvania: obese patients, obese patients with metabolic syndrome and non-obese individuals. The Old Order Amish are a genetically closed homogeneous Caucasian population of Central European ancestry ideal for genetic studies. These works have the potential to provide new mechanistic insights into the role of gut microflora in obesity and metabolic syndrome, a disease that is responsible for significant morbidity in the adult population, and may ultimately lead to novel approaches for prevention and treatment of this disorder.</p>
| phs000258 | dbGaP
Project description:gut leakage in mice with antibiotics and dextran sulfate
Project description:Altogether, this is the first study presenting the global changes of the transcriptome in the adrenal microvascular cells. The results of RNA sequencing and subsequent bioinformatics analysis revealed that adrenal vascular endothelial cells are active players not only involved in maintenance of the adrenal gland microenvironment, but also they play a key role in pathogen recognition and initiation of inflammation. However, our results also strongly suggest that systemic administration of LPS, which recapitulates to some degree situation in people with meningococcal sepsis, may develop certain damage, including vascular inflammation, hypoxia, blood coagulation and leakage. That may contribute to the adrenal dysfunction.