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Microbial Products (microbial + products)
Selected AbstractsEndoplasmic reticulum stress and the unfolded protein response are linked to synergistic IFN-, induction via X-box binding protein 1EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2008Judith A. Smith Dr. Abstract Type,I IFN are strongly induced upon engagement of certain pattern recognition receptors by microbial products, and play key roles in regulating innate and adaptive immunity. It has become apparent that the endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR), in addition to restoring ER homeostasis, also influences the expression of certain inflammatory cytokines. However, the extent to which UPR signaling regulates type,I IFN remains unclear. Here we show that cells undergoing a UPR respond to TLR4 and TLR3 ligands, and intracellular dsRNA, with log-fold greater IFN-, induction. This synergy is not dependent on autocrine type,I IFN signaling, but unexpectedly requires the UPR transcription factor X-box binding protein,1 (XBP-1). Synergistic IFN-, induction also occurs in HLA-B27/human ,2m-transgenic rat macrophages exhibiting a UPR as a consequence of HLA-B27 up-regulation, where it correlates with activation of XBP-1 splicing. Together these findings indicate that the cellular response to endogenous ,danger' that disrupts ER homeostasis is coupled to IFN-, induction by XBP-1, which has implications for the immune response and the pathogenesis of diseases involving the UPR. [source] Genomic variants of TLR1 , It takes (TLR-)two to tangoEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2007Abstract Toll-like receptors (TLR) are innate immune sensors of microbial cell wall products that initiate early host responses. The TLR2 receptor complex has been shown to contain heterodimers of TLR2 with either TLR1 or TLR6 enabling the host to detect different microbial molecules, such as lipopeptides of different chemical composition. In this issue of the European Journal of Immunology, an important role in the sensing of microbial products for I602S, a single nucleotide polymorphism (SNP) in human TLR1 has been identified. This result, in combination with another recently published report on this polymorphism elucidating a functional role in cell trafficking (surface expression of the receptor complex in individuals carrying the SNP was altered), provide genetic evidence affirming the important function of TLR1 as an essential co-receptor for TLR2. See accompanying article: http://dx.doi.org/10.1002/eji200737034 [source] TLR2 engagement on CD8 T cells lowers the thresholdfor optimal antigen-induced T cell activationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2006Anne Cottalorda Abstract TLR have a crucial role in the detection of microbial infection in mammals. Until recently, most investigations on TLR have focused on cells of the innate immune system and on the role of TLR in the initiation of antigen-specific responses following recognition of microbial products by APC. Here, we report that murine T cells express TLR1, TLR2, TLR6, TLR7 and TLR9 mRNA. Using CD8 T cells from F5 TCR-transgenic mice, we demonstrate that the lipopeptide Pam3CysSK4 (Pam), a synthetic analog of bacterial and mycoplasmal lipoproteins that recognizes TLR1/2 complex, costimulates antigen-activated T cells. Costimulation with Pam permits an increased cell proliferation and survival associated with a sustained CD25 expression and an enhanced expression of Bcl-xL anti-apoptotic protein. In addition, we show that costimulation with Pam up-regulates IFN-, production but also granzyme,B secretion and cytotoxic activity of antigen-activated T cells, indicating that TLR2 engagement enhances the major effector functions of CD8 T cells. Finally, we demonstrate that TLR2 engagement on T cells lowers the activation threshold for costimulatory signals delivered by APC. [source] Stabilization of organic matter in temperate soils: mechanisms and their relevance under different soil conditions , a reviewEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2006M. v. Lützow Summary Mechanisms for C stabilization in soils have received much interest recently due to their relevance in the global C cycle. Here we review the mechanisms that are currently, but often contradictorily or inconsistently, considered to contribute to organic matter (OM) protection against decomposition in temperate soils: (i) selective preservation due to recalcitrance of OM, including plant litter, rhizodeposits, microbial products, humic polymers, and charred OM; (ii) spatial inaccessibility of OM against decomposer organisms due to occlusion, intercalation, hydrophobicity and encapsulation; and (iii) stabilization by interaction with mineral surfaces (Fe-, Al-, Mn-oxides, phyllosilicates) and metal ions. Our goal is to assess the relevance of these mechanisms to the formation of soil OM during different stages of decomposition and under different soil conditions. The view that OM stabilization is dominated by the selective preservation of recalcitrant organic components that accumulate in proportion to their chemical properties can no longer be accepted. In contrast, our analysis of mechanisms shows that: (i) the soil biotic community is able to disintegrate any OM of natural origin; (ii) molecular recalcitrance of OM is relative, rather than absolute; (iii) recalcitrance is only important during early decomposition and in active surface soils; while (iv) during late decomposition and in the subsoil, the relevance of spatial inaccessibility and organo-mineral interactions for SOM stabilization increases. We conclude that major difficulties in the understanding and prediction of SOM dynamics originate from the simultaneous operation of several mechanisms. We discuss knowledge gaps and promising directions of future research. [source] Composition of organic matter in a subtropical Acrisol as influenced by land use, cropping and N fertilization, assessed by CPMAS 13C NMR spectroscopyEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2005J. Dieckow Summary We know much about the influence of management on stocks of organic matter in subtropical soils, yet little about the influence on the chemical composition. We therefore studied by CPMAS 13C NMR spectroscopy the composition of the above-ground plant tissue, of the organic matter of the whole soil and of silt- and clay-size fractions of the topsoil and subsoil of a subtropical Acrisol under grass and arable crops. Soil samples were collected from three no-till cropping systems (bare soil; oats,maize; pigeon pea + maize), each receiving 0 and 180 kg N ha,1 year,1, in a long-term field experiment. Soil under the original native grass was also sampled. The kind of arable crops and grass affected the composition of the particulate organic matter. There were no differences in the composition of the organic matter in silt- and clay-size fractions, or of the whole soil, among the arable systems. Changes were observed between land use: the soil of the grassland had larger alkyl and smaller aromatic C contents than did the arable soil. The small size fractions contain microbial products, and we think that the compositional difference in silt- and clay-size fractions between grassland and the arable land was induced by changes in the soil's microbial community and therefore in the quality of its biochemical products. The application of N did not affect the composition of the above-ground plant tissue nor of the particulate organic matter and silt-size fractions, but it did increase the alkyl C content in the clay-size fraction. In the subsoil, the silt-size fraction of all treatments contained large contents of aromatic C. Microscopic investigation confirmed that this derived from particles of charred material. The composition of organic matter in this soil is affected by land use, but not by variations in the arable crops grown. [source] Genetic improvement of processes yielding microbial productsFEMS MICROBIOLOGY REVIEWS, Issue 2 2006Jose L. Adrio Abstract Although microorganisms are extremely good in presenting us with an amazing array of valuable products, they usually produce them only in amounts that they need for their own benefit; thus, they tend not to overproduce their metabolites. In strain improvement programs, a strain producing a high titer is usually the desired goal. Genetics has had a long history of contributing to the production of microbial products. The tremendous increases in fermentation productivity and the resulting decreases in costs have come about mainly by mutagenesis and screening/selection for higher producing microbial strains and the application of recombinant DNA technology. [source] Interferon-, priming is involved in the activation of arginase by oligodeoxinucleotides containing CpG motifs in murine macrophagesIMMUNOLOGY, Issue 1pt2 2009Miriam V. Liscovsky Summary Recognition of microbial products by macrophages (M,) stimulates an inflammatory response and plays a critical role in directing the host immune response against infection. In the present work, we showed for the first time that synthetic oligodeoxynucleotides containing unmethylated cytosine guanine motifs (CpG) are able to stimulate, in the presence of interferon-, (IFN-,), both arginase and inducible nitric oxide synthase (iNOS) in murine M,. Unexpectedly, IFN-,, a cytokine believed to be an inhibitor of arginase activity, intervened in the activation of this enzyme. A significant increase in arginase activity was observed upon a short pre-incubation (1 hr) with IFN-, and subsequent CpG stimulation. Therefore, a very interesting observation of this study was that the CpG-mediated arginase activity is dependent on IFN-, priming. The increase in arginase activity as a result of stimulation with CpG plus IFN-,was correlated with augmented expression of the arginase II isoform. The use of pharmacological specific inhibitors revealed that arginase activity was dependent on p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated protein kinase (ERK), but independent of c-Jun N-terminal kinase (JNK) activation. This report reveals a singular effect of the combination of CpG and IFN-,, one of the mayor cytokines produced in response to CpG administration in vivo. [source] The modulatory effects of lipopolysaccharide-stimulated B cells on differential T-cell polarizationIMMUNOLOGY, Issue 2 2008Hui Xu Summary Lipopolysaccharide (LPS) is a major component of environmental microbial products. Studies have defined the LPS dose as a critical determining factor in driving differential T-cell polarization but the direct effects of LPS on individual antigen-presenting cells is unknown. Here, we investigated the effects of LPS doses on naive B cells and the subsequent modulatory effects of these LPS-activated B cells on T-cell polarization. The LPS was able to induce a proliferative response starting at a dose of 100 ng/ml and was capable of enhancing antigen internalization at a dose of 1 ,g/ml in naive B cells. Following LPS stimulation, up-regulation of the surface markers CD40, CD86, I-Ad, immunoglobulin M, CD54 and interleukin-10 production, accompanied by down-regulation of CD5 and CD184 (CXCR4) were observed in a LPS dose-dependent manner. Low doses (< 10 ng/ml) of LPS-activated B cells drove T helper type 2 polarization whereas high doses (> 0·1 ,g/ml) of LPS-activated B cells resulted in T regulatory type 1 cell polarization. In conclusion, LPS-activated B cells acquire differential modulatory effects on T-cell polarization. Such modulatory effects of B cells are dependent on the stimulation with LPS in a dose-dependent manner. These observations may provide one of the mechanistic explanations for the influence of environmental microbes on the development of allergic diseases. [source] Modeling and simulation of the formation and utilization of microbial products in aerobic granular sludgeAICHE JOURNAL, Issue 2 2010Bing-Jie Ni Abstract A mathematical model is established to simulate the formation of extracellular polymeric substances (EPS), soluble microbial products (SMP), and internal storage products (XSTO) in aerobic granular sludge. The sensitivity of these microbial products concentrations toward the key model parameters is analyzed. Independent experiments are conducted to find required parameter values and to test its predictive ability. The model is evaluated by using one-cycle operating experimental results of a lab-scale aerobic granule-based sequencing batch reactor (SBR) and batch experimental results. Results show that the model is able to describe the microbial product dynamics in aerobic granules and provide further insights into a granule-based SBR. The effect of the initial substrate and biomass concentrations on the formation of microbial products in aerobic granular sludge can therefore be analyzed by model simulation. A higher substrate concentration results in a greater concentration of EPS, SMP, and XSTO. An accumulation of biomass in the bioreactor leads to an increased production rate of EPS, SMP, and XSTO. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Specific immunotherapy suppresses Th2 responses via modulating TIM1/TIM4 interaction on dendritic cellsALLERGY, Issue 8 2010C.-Q. Zhao To cite this article: Zhao C-Q, Li T-L, He S-H, Chen X, An Y-F, Wu W-K, Zhou X-H, Li P, Yang P-C. Specific immunotherapy suppresses Th2 responses via modulating TIM1/TIM4 interaction on dendritic cells. Allergy 2010; 65: 986,995 Abstract Background:, Specific immunotherapy (SIT) is the only curable remedy for allergic disorders currently; however, the underlying mechanism is not fully understood yet. This study aimed to elucidate the mechanism of SIT on suppressing TIM4 (T cell immunoglobulin mucin domain molecule 4) expression in dendritic cells (DCs) and modulating the skewed T helper 2 (Th2) responses in patients with airway allergy. Methods:, Twenty patients with allergic rhinitis (AR) were treated with SIT for 3 months. Before and after SIT, the expression of TIM4 in peripheral DC and TIM1 in Th2 cells was examined. The role of Fc gamma receptor (Fc,R) I and II in modulating the expression of TIM4 in DCs was investigated. Results:, The interaction of TIM1/TIM4 played a critical role in sustaining the polarization status of Th2 cells in AR patients. Cross-linking Fc,RI by antigen/IgG complexes increased the production of TIM4 by dendritic cells via upregulating tumor necrosis factor-alpha in DCs. Exposure to microbial products promoted the expression of Fc,RI in DCs that further increased the expression of TIM4. Exposure to specific antigens alone upregulated the expression of Fc,RII in DCs, that suppressed the expression of TIM4. Conclusions:, We conclude that SIT suppresses the skewed Th2 responses via disrupting the interaction of TIM1/TIM4 in antigen-specific Th2 cells. [source] Childhood asthma epidemiology: Insights from comparative studies of rural and urban populations,PEDIATRIC PULMONOLOGY, Issue 2 2008Gary W.K. Wong MD Abstract Asthma is one of the most common chronic respiratory disorders. Many epidemiology studies have suggested an increasing trend of asthma in many different regions of the world but the exact reasons explaining such trend remain unclear. Nevertheless, changing environmental factors are most likely important in explaining the trend of asthma. Studies in the past decade have clearly shown a mark difference in the prevalence between urban and rural regions. The consistent findings of a markedly lower prevalence of asthma in children and adults who have been brought up in a farming environment clearly indicate the importance of environmental influence of asthma development. Although the exact protective environmental factors in the rural region remain to be defined, there have been many studies suggesting that early exposure to microbes or microbial products may play a role in modulating the immune system so as to reduce the future risk of asthma and allergies. Advances in the understanding of the genetic predisposition and how these genetic factors may interact with specific environment factors are of paramount importance for the future development of primary preventive strategies for asthma. Pediatr Pulmonol. 2008; 43:107,116. © 2007 Wiley-Liss, Inc. [source] Phytomodulatory potentials of Aloe vera against Salmonella OmpR -mediated inflammationPHYTOTHERAPY RESEARCH, Issue 8 2008Praveen Rishi Abstract Mediators released during inflammatory response play an essential role in eliminating microbes or microbial products. However, the uncontrolled release of cytotoxic substances characterized by extensive inflammation may adversely affect normal tissues. Under such conditions it is important to manage the hyperinflammation in order to change the clinical manifestations of the disease. Accordingly, the present study was designed to evaluate the modulation of Salmonella OmpR mediated inflammation by Aloe vera, a plant known to contain antiinflammatory ingredients. It was observed that outer-membrane proteins (OMPs) extracted from the wild type strain of S. typhimurium caused inflammation of greater magnitude compared with the OMPs extracted from its mutant construct as evident from the oedema test as well as the hyperalgesic (flicking) response of the animals under experimental conditions. However, Aloe vera applied topically, administered intraperitoneally or in combination modulated the inflammatory response. The maximum effect was observed with the combined formulation indicating modulation at local as well as systemic levels. The results reveal that this modulation could be due to the potential of Aloe vera to decrease peroxidative damage via a decrease in the levels of monokines (TNF- ,, IL-1 and IL-6) and an increase in the level of superoxide dismutase (SOD). Moreover, the presence of SOD in Aloe vera itself might be responsible for enhancing its levels in the macrophages. On the other hand, no significant change in the catalase activity was observed by Aloe vera treatment. The use of Aloe vera, therefore, seems to have a promising role in the modulation of Salmonella OmpR mediated inflammation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effect of D-mannitol on feed digestion and cecotrophic system in rabbitsANIMAL SCIENCE JOURNAL, Issue 2 2009Hamza HANIEH ABSTRACT This study aimed to evaluate the effect of sugar alcohol as an energy source for cecal microbes on digestibility, cecotrophy (i.e. reingestion of microbial products of cecum, cecotrophs) and performance in rabbits. Thus, we fed rabbits an experimental diet that included 5% of D-mannitol, and collected hard feces and cecotrophs to be analyzed for crude protein (CP), acid detergent fiber (ADF), ether extract (EE), crude ash (CA) and dry matter (DM). Cecotrophic behavior of the rabbits was also observed. Feeding D-mannitol increased (P < 0.01) digestibility of ADF, resulting in a decrease (P < 0.05) in the concentration in hard feces. The increase (P < 0.05) in CP concentration was attributed to lower (P < 0.05) digestibility. D-mannitol had a similar modulatory effect on CP and ADF concentrations in hard feces and cecotrophs. Accordingly, estimations of the proportion of nutrients recycled by cecotrophy to dietary intake (PR), obtained by the two calculation methods, showed an increase (P < 0.01) in PR of CP and a decrease (P < 0.05) in that of ADF. Daily weight gain and feed efficiency increased (P < 0.05) for D-mannitol-fed rabbits, while daily feed intake decreased (P < 0.05). These results suggest the possibility of using D-mannitol as a stimulator of cecal microbial growth and cellulolytic activity, and therefore, improved rabbits performance. [source] Bacterial vaginosis , a laboratory and clinical diagnostics enigma,APMIS, Issue 3 2005Review article II Diagnosing bacterial vaginosis (BV) has long been based on the clinical criteria of Amsel et al., whereby three of four defined criteria must be satisfied. Though there are other criteria and scoring methods which function well in comparison (i.e. Nugent scoring), it is not certain that they will always identify the same category of patients. Point-of-care methods based on various combinations of microbial products, presence of RNA, or more complex laboratory instrumentations such as sensor arrays, have also been introduced for the diagnosis of BV. No method for diagnosing BV can at present be regarded as the best. It could be that , based partly on tacit knowledge on the part of the clinical investigators scoring in the clinic , various scoring systems have been chosen to fit a particular BV-related problem in a particular population. In this review we critically examine these pertinent issues influencing clinical scoring and laboratory diagnostics of BV. [source] Evaluation of metabolism using stoichiometry in fermentative biohydrogenBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2009Hyung-Sool Lee Abstract We first constructed full stoichiometry, including cell synthesis, for glucose mixed-acid fermentation at different initial substrate concentrations (0.8,6 g-glucose/L) and pH conditions (final pH 4.0,8.6), based on experimentally determined electron-equivalent balances. The fermentative bioH2 reactions had good electron closure (,9.8 to +12.7% for variations in glucose concentration and ,3 to +2% for variations in pH), and C, H, and O errors were below 1%. From the stoichiometry, we computed the ATP yield based on known fermentation pathways. Glucose-variation tests (final pH 4.2,5.1) gave a consistent fermentation pattern of acetate,+,butyrate,+,large H2, while pH significantly shifted the catabolic pattern: acetate,+ butyrate,+,large H2 at final pH 4.0, acetate,+,ethanol,+ modest H2 at final pH 6.8, and acetate,+,lactate,+,trivial H2 at final pH 8.6. When lactate or propionate was a dominant soluble end product, the H2 yield was very low, which is in agreement with the theory that reduced ferredoxin (Fdred) formation is required for proton reduction to H2. Also consistent with this hypothesis is that high H2 production correlated with a high ratio of butyrate to acetate. Biomass was not a dominant sink for electron equivalents in H2 formation, but became significant (12%) for the lowest glucose concentration (i.e., the most oligotrophic condition). The fermenting bacteria conserved energy similarly at ,3 mol ATP/mol glucose (except 0.8 g-glucose/L, which had ,3.5 mol ATP/mol glucose) over a wide range of H2 production. The observed biomass yield did not correlate with ATP conservation; low observed biomass yields probably were caused by accelerated rates of decay or production of soluble microbial products. Biotechnol. Bioeng. 2009; 102: 749,758. © 2008 Wiley Periodicals, Inc. [source] | |||||||||||||