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Heat shock proteins (HSPs) are essential mediators of cellular homeostasis by maintaining protein functionality and stability, and activating appropriate immune cells. HSP activity is influenced by a variety of factors including diet,... more
Heat shock proteins (HSPs) are essential mediators of cellular homeostasis by maintaining protein functionality and stability, and activating appropriate immune cells. HSP activity is influenced by a variety of factors including diet, microbial stimuli, environment and host immunity. The overexpression and down-regulation of HSPs is associated with various disease phenotypes, including the inflammatory bowel diseases (IBD) such as Crohn’s disease (CD). While the precise etiology of CD remains unclear, many of the putative triggers also influence HSP activity. The development of different CD phenotypes therefore may be a result of the disease-modifying behavior of the environmentally-regulated HSPs. Understanding the role of bacterial and endogenous HSPs in host homeostasis and disease will help elucidate the complex interplay of factors. Furthermore, discerning the function of HSPs in CD may lead to therapeutic developments that better reflect and respond to the gut environment.
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In the pursuit to understand intestinal epithelial cell biology in health and disease, researchers have established various model systems, from whole animals (typically rodents) with experimentally induced disease to transformed human... more
In the pursuit to understand intestinal epithelial cell biology in health and disease, researchers have established various model systems, from whole animals (typically rodents) with experimentally induced disease to transformed human carcinomas. The obvious limitation to the ex vivo or in vitro cell systems was enriching, maintaining, and expanding differentiated intestinal epithelial cell types. The popular concession was human and rodent transformed cells of mainly undifferentiated cells, with a few select lines differentiating along the path to becoming goblet cells. Paneth cells, in particular, remained unculturable. The breakthrough came in the last decade with the report of conditions to grow mouse intestinal organoids. Organoids are 3-dimensional ex vivo “mini-organs” of the organ from which the stem cells were derived. Intestinal organoids contain fully differentiated epithelial cells in the same spatial organization as in the native epithelium. The cells are suitably polar...
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Enteropathogenic Escherichia coli (EPEC) are worldwide human enteric pathogens inflicting significant morbidity and causing large economic losses. A type 3 secretion system (T3SS) is critical for EPEC intestinal colonization, and... more
Enteropathogenic Escherichia coli (EPEC) are worldwide human enteric pathogens inflicting significant morbidity and causing large economic losses. A type 3 secretion system (T3SS) is critical for EPEC intestinal colonization, and injection of effectors into host cells contributes to cellular subversion and innate immune evasion. Here, we demonstrate that two strictly conserved C-terminal tyrosine residues, Y152 and Y153, within the multicargo T3SS chaperone CesT serve differential roles in regulating effector secretion in EPEC. Conservative substitution of both tyrosine residues to phenylalanine attenuated EPEC type 3 effector injection into host cells, and significantly limited Tir effector mediated intimate adherence, a key feature of attaching and effacing pathogenesis. Whereas CesT Y153 supported normal levels of Tir translocation, CesT Y152 was strictly required for the effector NleA to be expressed and subsequently translocated into host cells during infection. Other effectors...
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Enteropathogenic Escherichia coli (EPEC) use a type 3 secretion system (T3SS) for injection of effectors into host cells and intestinal colonization. Here, we demonstrate that the multicargo chaperone CesT has two strictly conserved... more
Enteropathogenic Escherichia coli (EPEC) use a type 3 secretion system (T3SS) for injection of effectors into host cells and intestinal colonization. Here, we demonstrate that the multicargo chaperone CesT has two strictly conserved tyrosine phosphosites, Y152 and Y153 that regulate differential effector secretion in EPEC. Conservative substitution of both tyrosine residues to phenylalanine strongly attenuated EPEC type 3 effector injection into host cells, and limited Tir effector mediated intimate adherence during infection. EPEC expressing a CesT Y152F variant were deficient for NleA effector expression and exhibited significantly reduced translocation of NleA into host cells during infection. Other effectors were observed to be dependent on CesT Y152 for maximal translocation efficiency. Unexpectedly, EPEC expressing a CesT Y153F variant exhibited significantly enhanced effector translocation of many CesT-interacting effectors, further implicating phosphosites Y152 and Y153 in C...
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Exclusive enteral nutrition (EEN) is a first-line therapy in pediatric Crohn's disease (CD) thought to induce remission through changes in the gut microbiome. With microbiome assessment largely focused on microbial taxonomy and... more
Exclusive enteral nutrition (EEN) is a first-line therapy in pediatric Crohn's disease (CD) thought to induce remission through changes in the gut microbiome. With microbiome assessment largely focused on microbial taxonomy and diversity, it remains unclear to what extent EEN induces functional changes that thereby contribute to its therapeutic effect. Fecal samples were collected from 15 pediatric CD patients prior to and after EEN treatment, as well as from 5 healthy controls. Metagenomic data were obtained via next-generation sequencing, and nonhuman reads were mapped to KEGG pathways, where possible. Pathway abundance was compared between CD patients and controls, and between CD patients that sustained remission (SR) and those that did not sustain remission (NSR). Of 132 KEGG pathways identified, 8 pathways differed significantly between baseline CD patients and controls. Examination of these eight pathways showed SR patients had greater similarity to controls than NSR patie...
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The intestinal epithelial cell (IEC) represents the first cellular barrier to infection. Consistent with this sentinel role, IEC are known to produce a variety of chemokines in response to bacterial infection or proinflammatory cytokines.... more
The intestinal epithelial cell (IEC) represents the first cellular barrier to infection. Consistent with this sentinel role, IEC are known to produce a variety of chemokines in response to bacterial infection or proinflammatory cytokines. These chemokines act as potent leukocyte activators and chemoattractants in vivo. In this report, we begin to characterize the regulation of expression of the chemokine monocyte chemoattractant protein-1 (MCP-1) in the rat small intestinal IEC-18 line. Following stimulation with either interleukin-1beta (IL-1beta) or lipopolysaccharide (LPS), IEC-18 cells produced MCP-1, with IL-1 proving a more effective stimulus than LPS at both the mRNA and protein levels. Expression of MCP-1 due to either stimulus was inhibited by tyrosine kinase inhibitors, prompting us to investigate potential phosphotyrosine-dependent targets responsible for MCP-1 expression. We detected activation of p38, a member of the mitogen-activated protein kinase family, following either IL-1 or LPS treatment. Specific inhibition of this kinase using the compound SB203580 caused a destabilization of MCP-1 mRNA. These data point to a role for p38 in the regulation of MCP-1 mRNA expression by the IEC.
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ABSTRACT
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Inflammatory bowel disease (IBD) is a family of disorders including ulcerative colitis and Crohn's disease that are characterized by chronic and relapsing intestinal inflammation. Increased production of proinflammatory mediators,... more
Inflammatory bowel disease (IBD) is a family of disorders including ulcerative colitis and Crohn's disease that are characterized by chronic and relapsing intestinal inflammation. Increased production of proinflammatory mediators, possibly combined with low expression of anti-inflammatory mediators, is thought to promote the development and progression of IBD. In the current study, we demonstrate that expression, secretion, and processing of chemerin, a potent chemoattractant for cells expressing chemokine-like receptor 1 (CMKLR1), increased in the cecum and colon along a gradient positively associated with the severity of inflammation in dextran sodium sulfate (DSS)-induced colitis. We also show that levels of circulating bioactive chemerin increased following DSS treatment. At both 6-8 and 14-16 weeks of age, CMKLR1 knockout mice developed signs of clinical illness more slowly than wild type and had changes in circulating cytokine levels, increased spleen weight, and increased...
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ABSTRACT
The acute inflammatory response is an organism's immediate reaction to injury. In mammals the response is facilitated by an abundance of molecules circulating in the plasma. These molecules are responsible for clotting the blood and... more
The acute inflammatory response is an organism's immediate reaction to injury. In mammals the response is facilitated by an abundance of molecules circulating in the plasma. These molecules are responsible for clotting the blood and chemotaxis of inflammatory cells. Polymorphonuclear leukocytes and monocytes usually comprise the cell infiltrate during acute inflammation. Within several hours of a localised injury and the
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We havecloned theregion spanning theputative promoter fromtwovariant surface glycoprotein gene expression sites that areateachendofchromosome M4ofTrypanosoma brucei IsTat 7.Bothexpression sites contain aretroposon-like sequence (ESR)... more
We havecloned theregion spanning theputative promoter fromtwovariant surface glycoprotein gene expression sites that areateachendofchromosome M4ofTrypanosoma brucei IsTat 7.Bothexpression sites contain aretroposon-like sequence (ESR) pseudogene whose3'endisapproximately 30bpupstream ofthe putative expression site promoter. TheESRsfrombothexpression sites share considerable sequence homology andarerelated toLINE-like elements, especially theT.brucei ingi retroposon. OtherESRsarelocated on large, butnotintermediate ormini-, chromosomes intheIsTaR1serodeme, andthetotal copynumberis10 to20,similar tothat estimated forvariant surface glycoprotein expression
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ABSTRACT It has been suggested that IBD involves altered interactions between genetically determined immune responses to environmental challenges such as gut bacteria. In order to determine if composition of gut microbiotas are related to... more
ABSTRACT It has been suggested that IBD involves altered interactions between genetically determined immune responses to environmental challenges such as gut bacteria. In order to determine if composition of gut microbiotas are related to genes associated with risk for developing CD, we assessed the microbiome in a cohort of 578 FDR of CD patients enriched for the genetic variations associated with an increased risk of CD. The subjects were selected from the GEM Project cohort on the basis of their ethnicity. Bacterial DNA was extracted from stool samples using QIAamp DNA Stool Mini Kit and V1-V3 hypervariable regions of bacterial 16S rRNA genes were sequenced using 454 pyrosequencing. These sequences were treated using the QIIME pipeline and USEARCH. The operational taxonomic units (OTUs) obtained were assigned to taxonomic classification using the RDP 2.2 and Greengenes (Feb 2011) core sequences. We analyzed the relationship of OTU composition with 30 of the most common disease-associated polymorphisms (SNPs) genotyped using Sequenom Gold iPlex or TaqMan platforms. The data were rarefied 50 times at equal sampling depth and statistical tests were done using ANOVA with p-value False Discovery Rate corrected for multiple comparisons (36x104). A total of 3,377,987 reads were obtained with an average of 4,286 ± 72 reads per subject. Overall, the dominant genera in these samples were Bacteroidetes, Faecalibacterium and Roseburia (23.9%±0.9, 18.0% ± 0.6, 12.3% ± 0.4 of total OTUs, respectively). Differences in the microbiome makeup were associated with two interleukin 23 receptor (IL23R) SNPs, rs11209026 and rs11465804. Heterozygotes for rs11209026 (reduced risk for CD) were associated with higher proportions of Bacteroides, Odoribacter and lower proportions of Clostridium, Faecalibacterium, Lachnospira, and Subdoligranulum (with a range of p=10-8 to 0.02). Similar results were obtained with rs11465804. In addition, risk alleles of NOD2, rs2066844 and rs2066847, were associated with higher proportions of Gammaproteobacteria (p<0.04). The immunity-related GTPase family M (IRGM) rs13361189 risk allele was associated with a lower proportion of Bacteroidia and an increase of Erysipelotrichi (p<0.03). The toll-like receptor 4 (TLR4) risk allele rs4986790 was associated with a higher proportion of Streptococceace (p<0.05). These results indicate differences exist in the intestinal microbiota which are associated with SNPs in IL23R, IRGM, NOD2 and TLR4. These results from healthy FDR differ from prior studies of changes in microbiota in patients with CD, potentially indicating that genetic associations with microbiota may be difficult to evaluate in the context of established inflammation. Our results represent the largest study defining the association between differences in the microbiota and host CD risk alleles in asymptomatic individuals.
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Interleukin 10-deficient mice (IL-10) are a popular model used to dissect the mechanisms underlying inflammatory bowel diseases. The role of complement, a host defense mechanism that bridges the innate and adaptive immune systems, has not... more
Interleukin 10-deficient mice (IL-10) are a popular model used to dissect the mechanisms underlying inflammatory bowel diseases. The role of complement, a host defense mechanism that bridges the innate and adaptive immune systems, has not been described in this model. We therefore studied the effect of deficiency of properdin, a positive regulator of complement, on colitis in mice with the IL-10 background. For acute colitis, IL-10 and IL-10/properdin double knockout (DKO) or radiation bone marrow-reconstituted chimeric mice, had piroxicam added to their powdered chow for 14 days. For chronic colitis, 2.5% dextran sodium sulfate was added to the animals' water for 4 days then the mice were killed 8 weeks later. Colons were assessed for inflammation, cell infiltration, and cytokine and complement measurements. Bacterial translocation was measured by cultivating bacteria from organs on Luria broth agar plates. C3a and C5a levels and C9 deposition were all increased in piroxicam-fed IL-10 mice compared with mice not fed piroxicam. Piroxicam-fed DKO mice lacked increased C5a and C9 deposition combined with exacerbated colitis, reduced numbers of infiltrating neutrophils, and markedly higher local and systemic bacterial numbers compared with IL-10 mice. Bone marrow cells from IL-10 mice were sufficient to restore protection against the heightened colitis in piroxicam-fed DKO mice. Complement is activated in the IL-10 mouse mucosa in a properdin-dependent manner. In the absence of terminal complement activation, the inflammation is heightened, likely due to a lack of neutrophil control over microbes escaping from the intestines.
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Trichinella spiralis occupies an intramulticellular niche in the small intestinal epithelium, and thus we examined the intestine and gut-associated tissues for proinflammatory cytokines during the infection. We document the patterns of... more
Trichinella spiralis occupies an intramulticellular niche in the small intestinal epithelium, and thus we examined the intestine and gut-associated tissues for proinflammatory cytokines during the infection. We document the patterns of interleukin-1 (IL-1), IL-6, gamma interferon, and tumor necrosis factor alpha mRNA expression in the duodenum, jejunum, Peyer's patches, mesenteric lymph node, spleen, and liver in T. spiralis-infected rats. By reverse transcription-PCR detection of mRNAs, IL-1beta was found increased in the jejunum but only on day 2. The jejunal IL-1beta increase was attributed to the epithelium by isolating epithelial cells and then depleting them of intraepithelial lymphocytes prior to analysis. The only cytokine for which mRNA was substantially increased in tissues later in infection was tumor necrosis factor alpha in the spleen and, to a lesser extent, in the mesenteric lymph node. In fact mRNA levels for some cytokines declined below uninfected levels in som...
Research Interests: Cytokines, Gene expression, Biological Sciences, Inflammatory Immune Response, Infection and immunity, and 13 moreAnimals, Male, mRna expression levels, Digestive System, Rats, Rat, Tumor necrosis factor-alpha, Epithelial Cell Biology, Trichinellosis, Small Intestine, Interleukin, Inflammatory response, and Medical and Health Sciences
We have identified a new variant surface glycoprotein expression site-associated gene (ESAG) in Trypanosoma brucei, the trypanosome leucine repeat (T-LR) gene. Like most other ESAGs, it is expressed in a life cycle stage-specific manner.... more
We have identified a new variant surface glycoprotein expression site-associated gene (ESAG) in Trypanosoma brucei, the trypanosome leucine repeat (T-LR) gene. Like most other ESAGs, it is expressed in a life cycle stage-specific manner. The N-terminal 20% of the predicted T-LR protein resembles the metal-binding domains of nucleic acid-binding proteins. The remainder is composed of leucine-rich repeats that are characteristic of protein-binding domains found in a variety of other eucaryote proteins. This is the first report of leucine-rich repeats and potential nucleic acid-binding domains on the same protein. The T-LR gene is adjacent to ESAG 4, which has homology to the catalytic domain of adenylate cyclase. This is intriguing, since yeast adenylate cyclase has a leucine-rich repeat regulatory domain. The leucine-rich repeat and putative metal-binding domains suggest a possible regulatory role that may involve adenylate cyclase activity or nucleic acid binding.
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We reported earlier that rat intestinal epithelial cells respond to helminth infection, to NSAID injury, and to detachment in vitro with expression of the IL-1RII. Now we have sought to determine whether human colon carcinoma cell lines... more
We reported earlier that rat intestinal epithelial cells respond to helminth infection, to NSAID injury, and to detachment in vitro with expression of the IL-1RII. Now we have sought to determine whether human colon carcinoma cell lines express, or may be induced to express, this potent IL-1 antagonist. Using RT-PCR, the T84 and HT-29 cell lines constitutively expressed mRNA for the membrane-bound, but not the secreted variant of the receptor. The protein was detectable by immunohistochemistry and was estimated to be 70 kDa by western blotting. TNF treatment of T84 cells led to slightly increased levels of IL-1RII mRNA and to significant increases in soluble protein detected in culture supernatants. Treating T84 cells with inhibitory anti-IL-1RII antibodies led to heightened responsiveness to IL-1, measured as IL-8 production. Expression of the IL-1RII by human epithelial cells has implications in terms of the IL-1 agonist versus antagonist balance in the diseased intestines.
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The intestinal epithelium has long been known to provide nonspecific defences such as mucus, lysozyme and transport of secretory immunoglobulin via the polyimmunoglobulin receptor. In the past decade, the realization emerged that... more
The intestinal epithelium has long been known to provide nonspecific defences such as mucus, lysozyme and transport of secretory immunoglobulin via the polyimmunoglobulin receptor. In the past decade, the realization emerged that enterocytes secrete molecules (cytokines) that regulate inflammation. As the focus tightened on this new role as sentinel, so has the interest in enterocyte production of cytokines with chemoattractant properties for leukocytes - the chemokines. Neutrophils are a prominent feature of the cellular infiltrate in various inflammatory diseases, and early reports indicated that epithelial cells secrete neutrophil chemoattractants. More recently, it has been shown that the cells also secrete chemokines for monocytes and lymphocytes. Some of these chemokines appear to be important in the uninflamed intestine but become increased during disease. While a great deal of knowledge has been gained regarding the circumstances leading to chemokine production by epithelial...
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TNF-alpha and IL-1beta promote leukocyte recruitment to arthritic joints and may contribute to cartilage degradation while regulatory cytokines such as IL-4 and IL-1RA may in part determine the course of arthritis. Here we report the... more
TNF-alpha and IL-1beta promote leukocyte recruitment to arthritic joints and may contribute to cartilage degradation while regulatory cytokines such as IL-4 and IL-1RA may in part determine the course of arthritis. Here we report the pattern of TNF-alpha, IL-1beta, IL-6, IFN-gamma, IL-1RA, and IL-4 mRNA expression, detected by RT/PCR, in the talar joint and draining popliteal lymph node (PLN) of rats with adjuvant arthritis (AA). Levels of TNF-alpha and IFN-gamma mRNA were increased in the PLN before clinical signs of arthritis. This was followed by increases in IL-1beta and IL-1RA mRNA at d9 and IL-6 mRNA at d12. PLN IL-1RA mRNA levels were positively correlated with those of IL-1beta and TNF-alpha throughout d5-d20. IL-4 mRNA levels were highest on days 7 and 20. In the synovium, a small increase in TNF-alpha, IL-1beta, and IL-6 mRNA was detected on d5 then again on d12. Maximal synovial TNF-alpha levels were reached on d20, while IL-1beta peak expression was on d16 and IL-6 on d1...
Research Interests: Immunology, Cytokines, Inflammation, Gene expression, Humans, and 15 moreAnimals, Male, Cyclosporine, Behavioral Animal Models, mRna expression levels, Rats, Lymph Node, Clinical Signs, Adjuvant Arthritis, Gene Expression Regulation, Interleukin, Interferon gamma, Lymph nodes, Immunosuppressive Agents, and Hypersensitivity Delayed
Interleukin 1 beta (IL-1 beta) is a potent inflammatory cytokine and IL-1 beta gene expression is elevated in the kidneys of mice with lupus nephritis. This study was designed to examine whether pharmacological administration of the IL-1... more
Interleukin 1 beta (IL-1 beta) is a potent inflammatory cytokine and IL-1 beta gene expression is elevated in the kidneys of mice with lupus nephritis. This study was designed to examine whether pharmacological administration of the IL-1 receptor antagonist (IL-1ra) would reduce the inflammation in MRL lpr/lpr mice with lupus nephritis. Human recombinant IL-1ra (RA) or saline (SA) was infused by intraperitoneal osmotic minipumps in 16 week old mice (n = 9, group RA or n = 12, group SA, respectively). Age matched MRL +/+ mice served as normal controls. At the end of 4 weeks of treatment glomerular filtration rates (5.4 +/- 0.4 vs 5.6 +/- 0.4 ml/min/kg BW), proteinuria (6.0 +/- 1.0 vs 5.5 +/- 1.2 micrograms IgG/day) glomerular volumes (571 +/- 30 vs 509 +/- 25 microns3 x 10(3)), mesangial volumes (172 +/- 23 vs 158 +/- 17 microns3 x 10(3)), and cells/glomerulus (519 +/- 51 vs 506 +/- 47) were not significantly different between RA and SA groups respectively. There was also no signific...
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We have cloned the region spanning the putative promoter from two variant surface glycoprotein gene expression sites that are at each end of chromosome M4 of Trypanosoma brucei IsTat 7. Both expression sites contain a retroposon-like... more
We have cloned the region spanning the putative promoter from two variant surface glycoprotein gene expression sites that are at each end of chromosome M4 of Trypanosoma brucei IsTat 7. Both expression sites contain a retroposon-like sequence (ESR) pseudogene whose 3' end is approximately 30 bp upstream of the putative expression site promoter. The ESRs from both expression sites share considerable sequence homology and are related to LINE-like elements, especially the T. brucei ingi retroposon. Other ESRs are located on large, but not intermediate or mini-, chromosomes in the IsTaR 1 serodeme, and the total copy number is 10 to 20, similar to that estimated for variant surface glycoprotein expression sites. No DNA rearrangements in the vicinity of the ESR and putative expression site promoter were detected following antigenic switches in the IsTaR 1 serodeme. ESR transcripts are present in bloodstream, but not procyclic, forms. Variation in transcript size and sequence between ...
Research Interests: Gene expression, Biological Sciences, Molecular and cellular biology, Animals, Polymerase Chain Reaction, and 9 moreMolecular cloning, Trypanosoma brucei brucei, Amino Acid Sequence, Base Sequence, Pseudogenes, Gene Expression Regulation, Molecular Sequence Data, Restriction Mapping, and Medical and Health Sciences
The epithelium has long been regarded as a passive barrier intended to protect the underlying tissues. Many regulatory signals, including cytokines, that control epithelial cell proliferation and differentiation and cell function during... more
The epithelium has long been regarded as a passive barrier intended to protect the underlying tissues. Many regulatory signals, including cytokines, that control epithelial cell proliferation and differentiation and cell function during inflammation were thought to be nonepithelial-derived. Now there is a growing appreciation that epithelial cells provide some of the impetus for their own growth and differentiation, and may also regulate the function of other cells through the elaboration of certain cytokines. Moreover, because epithelial cells serve as the interface between the organism and environment, they are in a position to signal changes in the environment. It is now clear that epithelial cells respond to injury or infection with cytokine secretion. Various approaches to detecting cytokines in normal and diseased tissue have been undertaken during the past few years to establish cytokine synthesis by different epithelial. This review will examine these recent investigations i...
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Clearance of Listeria monocytogenes in experimental models of infection has underscored the importance of interferon-gamma (IFN-gamma) in host resistance to intracellular pathogens. Because L. monocytogenes infections are more severe in... more
Clearance of Listeria monocytogenes in experimental models of infection has underscored the importance of interferon-gamma (IFN-gamma) in host resistance to intracellular pathogens. Because L. monocytogenes infections are more severe in newborns than adults, we compared IFN-gamma accumulation in the supernatants of mononuclear cells infected in vitro from newborns with those from adults. Supernatants were assayed for IFN-gamma using an enzyme-linked immunosorbent assay. Uninfected newborn and adult mononuclear cells had less than 50 pg/ml of IFN-gamma at all times tested. IFN-gamma levels in supernatants from infected adult mononuclear cells at 24 h of culture (1.15 x 10(3) +/- 0.92 pg/ml) were greater than supernatants from infected newborn mononuclear cells (0.19 x 10(3) +/- 0.33 pg/ml). IFN-gamma concentrations in newborn cell cultures plateaued on day 3 of culture (1.6 x 10(3) +/- 1.1 pg/ml) and were not significantly less than concentrations from adult cells. However, adult cel...
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Alveolar macrophages (AM) can be stimulated in vitro with material such as lipopolysaccharide, and this activation releases cytokines, collectively called interleukin-1, that can stimulate local cells such as fibroblasts, systemic cells... more
Alveolar macrophages (AM) can be stimulated in vitro with material such as lipopolysaccharide, and this activation releases cytokines, collectively called interleukin-1, that can stimulate local cells such as fibroblasts, systemic cells such as lymphocytes, and/or distant parenchymal cells such as hepatocytes. During murine infection with the nematode Nippostrongylus brasiliensis, AM are activated as the parasite larvae migrate through the lung. We examined AM for unstimulated release of lymphocyte-activating factor (LAF) and hepatocyte-stimulating factor (HSF) as evidence of in vivo activation. Two days after infection, marked unstimulated release of LAF was demonstrated along with a smaller increase in unstimulated release of HSF activity. Release of both activities could be further augmented by in vitro stimulation with lipopolysaccharide. Eight days after infection unstimulated HSF activity was even higher than on Day 2, whereas unstimulated LAF release returned to normal. These...
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In considering the pathology associated with infectious diseases, the most common host response to such infection is inflammation. The mechanism(s) whereby inflammation is initiated and the cell types involved will dictate the kinds of... more
In considering the pathology associated with infectious diseases, the most common host response to such infection is inflammation. The mechanism(s) whereby inflammation is initiated and the cell types involved will dictate the kinds of acute phase plasma changes that can be seen associated with the infection. Bacteria seem to initiate the classical type of inflammatory response and plasma protein changes similar to those seen in experimental inflammation induced by chemical means. Viruses, on the other hand, in the absence of cytopathology do not appear to induce the same kind of inflammatory changes and avoid the induction of the acute phase protein response since they may not initiate activation of monocytes and/or macrophages. Those viruses that do cause macrophage activation would be expected to have acute phase protein changes associated with that activation. Parasites, however, appear to initiate the acute phase plasma response only when their migration leads to tissue destruc...
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During acute inflammation, the mammalian liver responds with increased production and secretion of a series of plasma glycoproteins, collectively termed the acute-phase proteins, resulting from the release at the site of inflammation of... more
During acute inflammation, the mammalian liver responds with increased production and secretion of a series of plasma glycoproteins, collectively termed the acute-phase proteins, resulting from the release at the site of inflammation of polypeptide cytokines, including IL-1 and IL-6, which interact with receptors on hepatocytes and alter gene expression. This attribute of the systemic acute-phase response was studied throughout the course of infection with two nematode parasites in rats. Significant increases in serum haptoglobin, alpha 1-acid glycoprotein and alpha 1-cysteine protease inhibitor were detected coincident with episodes of skin, lung and intestinal pathology during Nippostrongylus brasiliensis, but were not seen during Trichinella spiralis, infection of the rat despite similar intestinal pathology. These changes were seen at both the protein and mRNA levels in the liver. Infection with T. spiralis was not anti-inflammatory, as macrophages from various sites could be in...
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Regulatory B (Breg) cells are known to modulate immune responses through predominantly interleukin-10 (IL-10)-dependent mechanisms and can be hypothetically divided into innate and adaptive subsets based on the nature of their activating... more
Regulatory B (Breg) cells are known to modulate immune responses through predominantly interleukin-10 (IL-10)-dependent mechanisms and can be hypothetically divided into innate and adaptive subsets based on the nature of their activating signals. However, the specific role of different Breg subsets in modulating immune responses remains ambiguous. Here we have shown that Chlamydia induces IL-10-producing splenic B-cell populations consisting of CD43(+) and CD43(-) subsets of IgM(hi)IgD(lo) innate-like B (ILB) cells in vitro. While CD43(+)IL-10-producing B cells displayed innate type features and were readily induced by Chlamydia via Toll-like-receptor (TLR) signaling, CD43(-)IL-10-producing B cells required additional B-cell activating factor (BAFF)-mediated signals from dendritic cells (DCs) for their differentiation and activation, thereby classifying them as adaptive type Bregs. Importantly, CD43(-), but not CD43(+), IL-10-producing ILB cells displayed bona fide Breg activity by ...
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Pathogenic bacteria introduce effector proteins directly into the cytosol of eukaryotic cells to promote invasion and colonization. OspG, a Shigella spp. effector kinase, plays a role in this process by helping to suppress the host... more
Pathogenic bacteria introduce effector proteins directly into the cytosol of eukaryotic cells to promote invasion and colonization. OspG, a Shigella spp. effector kinase, plays a role in this process by helping to suppress the host inflammatory response. OspG has been reported to bind host E2 ubiquitin-conjugating enzymes activated with ubiquitin (E2~Ub), a key enzyme complex in ubiquitin transfer pathways. A co-crystal structure of the OspG/UbcH5c~Ub complex reveals that complex formation has important ramifications for the activity of both OspG and the UbcH5c~Ub conjugate. OspG is a minimal kinase domain containing only essential elements required for catalysis. UbcH5c~Ub binding stabilizes an active conformation of the kinase, greatly enhancing OspG kinase activity. In contrast, interaction with OspG stabilizes an extended, less reactive form of UbcH5c~Ub. Recognizing conserved E2 features, OspG can interact with at least ten distinct human E2s~Ub. Mouse oral infection studies in...
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There is a paucity of comprehensive studies of the APP response in parasitic infection. This should be remedied for two reasons. First, as there is a limited number of cytokines with hepatocyte-stimulating activities, and as each one... more
There is a paucity of comprehensive studies of the APP response in parasitic infection. This should be remedied for two reasons. First, as there is a limited number of cytokines with hepatocyte-stimulating activities, and as each one elicits a unique spectrum of protein changes, examination of the APP response during infection could provide insight into the cytokines involved. Second, the presence of IL-1, IL-6 and TNF, the mediators of the APR, in tissues and circulation have important implications for subsequent immune responses.
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The cytochemical and functional characteristics of broncho-alveolar multinucleate giant cells and the kinetics of the giant cell response in the lungs of mice and rats during Nippostrongylus brasiliensis infection were studied. Primary... more
The cytochemical and functional characteristics of broncho-alveolar multinucleate giant cells and the kinetics of the giant cell response in the lungs of mice and rats during Nippostrongylus brasiliensis infection were studied. Primary infections resulted in significantly increased numbers of recoverable giant cells for up to 30 and 50 days in rats and mice, respectively. During secondary infections in the rat the giant cell response was more rapid and greater in magnitude than in a primary infection, suggesting that it was immunologically mediated. The giant cells displayed decreased C3- and IgG-dependent binding or phagocytic potential compared with mononucleate alveolar macrophages. Fusion of mononucleate alveolar macrophages into giant cells may therefore compromise complement and antibody dependent helminthocidal activity of these cells.