bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production of Matrix Metalloproteinases in Response to Mycobacterial Infection
Authors: Quiding-Järbrink Marianne , Smith Debbie A. , Bancroft Gregory J. 
Published: July 2002

ABSTRACTMatrix metalloproteinases (MMPs) constitute a large family of enzymes with specificity for the various proteins of the extracellular matrix which are implicated in tissue remodeling processes and chronic inflammatory conditions. To investigate the role of MMPs in immunity to mycobacterial infections, we incubated murine peritoneal macrophages with viableMycobacterium bovisBCG orMycobacterium tuberculosisH37Rv and assayed MMP activity in the supernatants by zymography. Resting macrophages secreted only small amounts of MMP-9 (gelatinase B), but secretion increased dramatically in a dose-dependent manner in response to either BCG orM. tuberculosisin vitro. Incubation with mycobacteria also induced increased MMP-2 (gelatinase A) activity. Neutralization of tumor necrosis alpha (TNF-α), and to a lesser extent interleukin 18 (IL-18), substantially reduced MMP production in response to mycobacteria. Exogenous addition of TNF-α or IL-18 induced macrophages to express MMPs, even in the absence of bacteria. The immunoregulatory cytokines gamma interferon (IFN-γ), IL-4, and IL-10 all suppressed BCG-induced MMP production, but through different mechanisms. IFN-γ treatment increased macrophage secretion of TNF-α but still reduced their MMP activity. Conversely, IL-4 and IL-10 seemed to act by reducing the amount of TNF-α available to the macrophages. Finally, infection of BALB/c or severe combined immunodeficiency (SCID) mice with either BCG orM. tuberculosisinduced substantial increases in MMP-9 activity in infected tissues. In conclusion, we show that mycobacterial infection induces MMP-9 activity both in vitro and in vivo and that this is regulated by TNF-α, IL-18, and IFN-γ. These findings indicate a possible contribution of MMPs to tissue remodeling processes that occur in mycobacterial infections.
Lipopolysaccharides from Periodontopathic BacteriaPorphyromonas gingivalisandCapnocytophaga ochraceaAre Antagonists for Human Toll-Like Receptor 4
Authors: Yoshimura Atsutoshi , Kaneko Takashi , Kato Yoshifumi , Golenbock Douglas T. , Hara Yoshitaka 
Published: July 2002

ABSTRACTToll-like receptors (TLRs) 2 and 4 have recently been identified as possible signal transducers for various bacterial ligands. To investigate the roles of TLRs in the recognition of periodontopathic bacteria by the innate immune system, a Chinese hamster ovary (CHO) nuclear factor-κB (NF-κB)-dependent reporter cell line, 7.7, which is defective in both TLR2- and TLR4-dependent signaling pathways was transfected with human CD14 and TLRs. When the transfectants were exposed to freeze-dried periodontopathic bacteria,Actinobacillus actinomycetemcomitans,Porphyromonas gingivalis,Capnocytophaga ochracea, andFusobacterium nucleatum, and a non-oral bacterium,Escherichia coli, all species of the bacteria induced NF-κB-dependent CD25 expression in 7.7/huTLR2 cells. Although freeze-driedA.actinomycetemcomitans,F.nucleatum, andE.colialso induced CD25 expression in 7.7/huTLR4 cells, freeze-driedP.gingivalisdid not. Similarly, lipopolysaccharides (LPS) extracted fromA.actinomycetemcomitans,F.nucleatum, andE.coliinduced CD25 expression in 7.7/huTLR4 cells, but LPS fromP.gingivalisandC.ochraceadid not. Furthermore, LPS fromP.gingivalisandC.ochraceaattenuated CD25 expression in 7.7/huTLR4 cells induced by repurified LPS fromE.coli. LPS fromP.gingivalisandC.ochraceaalso inhibited the secretion of interleukin-6 (IL-6) from U373 cells, the secretion of IL-1β from human peripheral blood mononuclear cells, and ICAM-1 expression in human gingival fibroblasts induced by repurified LPS fromE.coli. These findings indicated that LPS fromP.gingivalisandC.ochraceaworked as antagonists for human TLR4. The antagonistic activity of LPS from these periodontopathic bacteria may be associated with the etiology of periodontal diseases.
Production of Prostaglandins and Leukotrienes by Pathogenic Fungi
Authors: Noverr Mairi C. , Toews Galen B. , Huffnagle Gary B. 
Published: July 2002

ABSTRACTThese studies demonstrate that pathogenic fungi (dermatophytic, subcutaneous, and systemic) have the ability to produce eicosanoids both from simple metabolites and from arachidonic acid. Host-derived eicosanoids have been previously demonstrated to enhance fungal colonization and atopic disease development. Thus, fungus-derived eicosanoids represent a potential class of novel virulence factors.
Cell Differentiation Is a Key Determinant of Cathelicidin LL-37/Human Cationic Antimicrobial Protein 18 Expression by Human Colon Epithelium
Authors: Hase Koji , Eckmann Lars , Leopard John D. , Varki Nissi , Kagnoff Martin F. 
Published: July 2002

ABSTRACTAntimicrobial peptides are highly conserved evolutionarily and are thought to play an important role in innate immunity at intestinal mucosal surfaces. To better understand the role of the antimicrobial peptide human cathelicidin LL-37/human cationic antimicrobial protein 18 (hCAP18) in intestinal mucosal defense, we characterized the regulated expression and production of this peptide by human intestinal epithelium. LL-37/hCAP18 is shown to be expressed within epithelial cells located at the surface and upper crypts of normal human colon. Little or no expression was seen within the deeper colon crypts or within epithelial cells of the small intestine. Paralleling its expression in more differentiated epithelial cells in vivo, LL-37/hCAP18 mRNA and protein expression was upregulated in spontaneously differentiating Caco-2 human colon epithelial cells and in HCA-7 human colon epithelial cells treated with the cell differentiation-inducing agent sodium butyrate. LL-37/hCAP18 expression by colon epithelium does not require commensal bacteria, since LL-37/hCAP18 is produced with a similar expression pattern by epithelial cells in human colon xenografts that lack a luminal microflora. LL-37/hCAP18 mRNA was not upregulated in response to tumor necrosis factor alpha, interleukin 1α (IL-1α), gamma interferon, lipopolysaccharide, or IL-6, nor did the expression patterns and levels of LL-37/hCAP18 in the epithelium of the normal and inflamed colon differ. On the other hand, infection of HCA-7 cells withSalmonella entericaserovar Dublin or enteroinvasiveEscherichia colimodestly upregulated LL-37/hCAP18 mRNA expression. We conclude that differentiated human colon epithelium expresses LL-37/hCAP18 as part of its repertoire of innate defense molecules and that the distribution and regulated expression of LL-37/hCAP18 in the colon differs markedly from that of other enteric antimicrobial peptides, such as defensins.
Genomic Localization of a T Serotype Locus to a Recombinatorial Zone Encoding Extracellular Matrix-Binding Proteins in
Streptococcus pyogenes
Authors: Bessen Debra E. , Kalia Awdhesh 
Published: July 2002

ABSTRACT

Streptococcus pyogenes
is an important bacterial pathogen afflicting humans. A striking feature is its extraordinary biological diversity, evident in the wide range of diseases it can cause and the antigenic heterogeneity present on its surface. The T antigens form the basis of a major serological typing scheme that is often used as an alternative or supplement to M typing. Unlike M typing, the genetic basis for T typing is poorly understood. In this report, the
tee6
gene is localized to a position ≈3.3 kb downstream from
prtF1
(or
sfbI
), which encodes the Fn-binding protein, protein F, a key virulence factor. Comparison of this portion of the genome with those of four additional strains reveals the presence of genes encoding a collagen-binding protein (Cpa) and a second Fn-binding protein (PrtF2 or PfbpI). This chromosomal region—here designated the FCT region—is ≈11 to 16 kb in length and is flanked at both ends by long stretches of highly conserved sequence. For each of the five strains, the FCT region contains a unique combination of semiconserved loci, indicative of extensive intergenomic recombination. The data provide evidence that the highly recombinatorial FCT region of the
S. pyogenes
genome is under strong selection for change in response to the host environment.
Monoclonal Antibody against thePlasmodium falciparumChitinase, PfCHT1, Recognizes a Malaria Transmission-Blocking Epitope inPlasmodium gallinaceumOokinetes Unrelated to the Chitinase PgCHT1
Authors: Langer Rebecca C. , Li Fengwu , Popov Vsevolod , Kurosky Alexander , Vinetz Joseph M. 
Published: July 2002

ABSTRACTTo initiate invasion of the mosquito midgut,Plasmodiumookinetes secrete chitinases that are necessary to cross the chitin-containing peritrophic matrix en route to invading the epithelial cell surface. To investigate chitinases as potential immunological targets of blocking malaria parasite transmission to mosquitoes, a monoclonal antibody (MAb) was identified that neutralized the enzymatic activity of the sole chitinase ofPlasmodium falciparum, PfCHT1, identified to date. This MAb, designated 1C3, previously shown to react with an apical structure ofP. falciparumookinetes, also reacts with a discrete apical structure ofP. gallinaceumookinetes. In membrane feeding assays, MAb 1C3 markedly inhibitedP. gallinaceumoocyst development in mosquito midguts. MAb 1C3 affinity isolated an ∼210-kDa antigen which, under reducing conditions, became a 35-kDa antigen. This isolated 35-kDa protein cross-reacted with an antiserum raised against a synthetic peptide derived from theP. gallinaceumchitinase active site, PgCHT1, even though MAb 1C3 did not recognize native or recombinant PgCHT1 on Western blot. Therefore, this affinity-purified 35-kDa antigen appears similar to a previously identified protein, PgCHT2, a putative second chitinase ofP. gallinaceum. Epitope mapping indicated MAb 1C3 recognized a region of PfCHT1 that diverges from a homologous amino acid sequence conserved within sequenced chitinases ofP. berghei, P. yoelii, andP. gallinaceum(PgCHT1). A synthetic peptide derived from the mapped 1C3 epitope may be useful as a component of a subunit transmission-blocking vaccine.
Porphyromonas gingivalisLipopolysaccharide Is Both Agonist and Antagonist for p38 Mitogen-Activated Protein Kinase Activation
Authors: Darveau Richard P. , Arbabi Saman , Garcia Iris , Bainbridge Brian , Maier Ronald V. 
Published: July 2002

ABSTRACTLipopolysaccharide (LPS) is a key inflammatory mediator. It has been proposed to function as an important molecule that alerts the host of potential bacterial infection. Although highly conserved, LPS contains important structural differences among different bacterial species that can significantly alter host responses. For example, LPS obtained fromPorphyromonas gingivalis, an etiologic agent for periodontitis, evokes a highly unusual host cell response. Human monocytes respond to this LPS by the secretion of a variety of different inflammatory mediators, while endothelial cells do not. In addition,P. gingivalisLPS inhibits endothelial cell expression of E-selectin and interleukin 8 (IL-8) induced by other bacteria. In this report the ability ofP. gingivalisLPS to activate p38 mitogen-activated protein (MAP) kinase was investigated. It was found that p38 MAP kinase activation occurred in response toP. gingivalisLPS in human monocytes. In contrast, no p38 MAP kinase activation was observed in response toP. gingivalisLPS in human endothelial cells or CHO cells transfected with human Toll-like receptor 4 (TLR-4). In addition,P. gingivalisLPS was an effective inhibitor ofEscherichia coli-induced p38 MAP kinase phosphorylation in both endothelial cells and CHO cells transfected with human TLR-4. These data demonstrate thatP. gingivalisLPS activates the LPS-associated p38 MAP kinase in monocytes and that it can be an antagonist forE. coliLPS activation of p38 MAP kinase in endothelial and CHO cells. These data also suggest that although LPS is generally considered a bacterial component that alerts the host to infection, LPS fromP. gingivalismay selectively modify the host response as a means to facilitate colonization.
Role of Gamma Interferon inHelicobacter pyloriInduction of Inflammatory Mediators during Murine Infection
Authors: Obonyo Marygorret , Guiney Donald G. , Harwood Julia , Fierer Joshua , Cole Sheri P. 
Published: July 2002

ABSTRACTGamma interferon (IFN-γ) has been proposed to play an important role inHelicobacter-related gastritis. Using the IFN-γ gene knockout (IFN-γ−/−) mouse model and a murine gastric epithelial cell line, GSM06, we demonstrated thatHelicobacter pylorimaximally induced macrophage inflammatory protein-2 (MIP-2) and inducible nitric oxide synthase (iNOS) mRNA only in wild-type mice. MIP-2 and iNOS mRNA were also induced byH. pyloriin GSM06 cells. Induction of cyclooxygenase 2 mRNA through IFN-γ was demonstrated in GSM06 cells. These data indicate that IFN-γ mediates the induction of MIP-2 and iNOS mRNA expression byH. pyloriin mice.
Role of Signal Sequence in Vaccine-Induced Protection against Experimental Coccidioidomycosis
Authors: Jiang Chengyong , Magee D. Mitchell , Ivey F. Douglas , Cox Rebecca A. 
Published: July 2002

ABSTRACTThe vaccine efficacy of the gene sequence encoding the signal peptide of the antigen known as antigen 2 or proline-rich antigen (Ag2/PRA), an immunodominant antigen present in the cell wall of the fungal pathogenCoccidioides immitis, was investigated in a murine model of coccidioidomycosis. Expression plasmids for Ag2/PRA(1-18) DNA (signal sequence), Ag2/PRA(19-194) DNA (lacking the signal sequence), and Ag2/PRA(1-194) DNA (full length) were inserted in the pVR1012 vector, and the constructs were used to vaccinate the highly susceptible BALB/c mouse strain. Immunization with the signal gene sequence significantly reduced the fungal burden in the lungs and spleens of mice 12 days after intraperitoneal challenge with a lethal dose of 2,500C. immitisarthroconidia, to a level comparable to the protection induced in mice immunized with the full-length Ag2/PRA(1-194) DNA. The Ag2/PRA(19-194) gene protected mice but to a significantly lower level than the signal sequence or the full-length Ag2 gene. The immunizing capacity of Ag2/PRA(1-18) was not attributable to a nonspecific immunostimulatory effect of DNA, as evidenced by the fact that mice immunized with a frameshift mutation of Ag2/PRA(1-18) were not protected against challenge. Furthermore, a synthetic peptide corresponding to the translated sequence of Ag2/PRA(1-18) DNA protected mice, albeit at a lower level than the Ag2/PRA(1-18) DNA vaccine. The protection induced with the signal gene vaccine correlated with the production of gamma interferon when splenocytes from Ag2/PRA(1-18)-immunized mice were stimulated with recombinant full-length Ag2 and was not associated with the production of anti-Coccidioidesimmunoglobulin G antibody. This is the first study to establish that a signal peptide sequence alone, administered as a gene vaccine or synthetic peptide, can induce protective immunity against a microbial pathogen.
Cellular and Molecular Regulation of Vaccination with Heat Shock Protein 60 fromHistoplasma capsulatum
Authors: Deepe, Jr., George S. , Gibbons Reta S. 
Published: July 2002

ABSTRACTVaccination with heat shock protein 60 (Hsp60) fromHistoplasma capsulatuminduces a protective immune response in mice. We explored the cellular and molecular requirements for the efficacy of recombinant Hsp60 in mice. Depletion of CD4+, but not CD8+, cells during the inductive phase of vaccination abolished protection, as assessed by survival and by the fungal burden in lungs and spleens. In the expressive phase, the elimination of CD4+or CD8+cells after immunization did not significantly alter fungal recovery or survival from a lethal challenge. Depletion of both subpopulations after Hsp60 vaccination resulted in a failure to control a lethal infection and a higher fungal burden in lungs and spleens. Cytokine release by spleen cells from mice vaccinated with Hsp60 produced substantially more gamma interferon and interleukin-10 and -12 than that of cells from mice immunized with eitherH. capsulatumrecombinant Hsp70 or bovine serum albumin. The generation of gamma interferon, but not of interleukin-10, was dependent on T cells, in particular CD4+cells. Treatment of Hsp60-immunized mice with monoclonal antibody to gamma interferon or interleukin-10 or -12 in the inductive phase of vaccination was accompanied by increased recovery of yeast cells from lungs and spleens and 100% mortality. Likewise, the neutralization of gamma interferon or interleukin-12 abolished the protective effect of Hsp60 in the expressive phase. These results delineate the complexity of the regulatory elements necessary for vaccination against this fungus.
Hierarchy of Susceptibility of Dendritic Cell Subsets to Infection byLeishmania major: Inverse Relationship to Interleukin-12 Production
Authors: Henri Sandrine , Curtis Joan , Hochrein Hubertus , Vremec David , Shortman Ken , Handman Emanuela 
Published: July 2002

ABSTRACTDendritic cells (DCs) are professional antigen-presenting cells which initiate and regulate T-cell immune responses. Here we show that murine splenic DCs can be ranked on the basis of their ability to phagocytose and harbor the obligately intracellular parasiteLeishmania major.CD4+CD8−DCs are the most permissive host cells forL. majoramastigotes, followed by CD4−CD8−DCs; CD4−CD8+cells are the least permissive. However, the least susceptible CD4−CD8+DC subset was the best interleukin-12 producer in response to infection. Infection did not induce in any DC subset production of the proinflammatory cytokine gamma interferon and nitric oxide associated with the induction of Th1 responses. The number of parasites phagocytosed by DCs was low, no more than 3 organisms per cell, compared to more than 10 organisms per macrophage. In infected DCs, the parasites are located in a parasitophorous vacuole containing both major histocompatibility complex (MHC) class II and lysosome-associated membrane protein 1 molecules, similar to their location in the infected macrophage. The parasite-driven redistribution of MHC class II to this compartment indicates that infected DCs should be able to present parasite antigen.
Efficient Spore Synthesis in
Bacillus subtilis
Depends on the CcdA Protein
Authors: Schiött Torbjörn , Hederstedt Lars 
Published: July 2002

ABSTRACT

CcdA is known to be required for the synthesis of
c
-type cytochromes in
Bacillus subtilis
, but the exact function of this membrane protein is not known. We show that CcdA also plays a role in spore synthesis. The expression of
ccdA
and the two downstream genes
yneI
and
yneJ
was analyzed. There is a promoter for each gene, but there is only one transcription terminator, located after the
yneJ
gene. The promoter for
ccdA
was found to be weak and was active mainly during the transition from exponential growth to stationary phase. The promoters for
yneI
and
yneJ
were both active in the exponential growth phase. The levels of the CcdA and YneJ proteins in the membrane were consistent with the observed promoter activities. The
ccdA
promoter activity was independent of whether the
ccdA-yneI-yneJ
gene products were absent or overproduced in the cell. It is shown that the four known cytochromes
c
in
B. subtilis
and the YneI and YneJ proteins are not required for sporulation. The combined data from analysis of sporulation-specific sigma factor activity, resistance properties of spores, and spore morphology indicate that CcdA deficiency affects stage V in sporulation. We conclude that CcdA, YneI, and YneJ are functionally unrelated proteins and that the role of CcdA in cytochrome
c
and spore synthesis probably relates to sulfhydryl redox chemistry on the outer surface of the cytoplasmic membrane.
Cross-Pathway Regulation in
Saccharomyces cerevisiae
: Activation of the Proline Utilization Pathway by Gal4p In Vivo
Authors: D'Alessio Michael , Brandriss Marjorie C. 
Published: July 2002

ABSTRACT

The Put3p and Gal4p transcriptional activators are members of a distinct class of fungal regulators called the Cys
6
Zn(II)
2
binuclear cluster family. This family includes over 50 different
Saccharomyces cerevisiae
proteins that share a similar domain organization. Gal4p activates the genes of the galactose utilization pathway permitting the use of galactose as the sole source of carbon and energy. Put3p controls the expression of the proline utilization pathway that allows yeast cells to grow on proline as the sole nitrogen source. We report that Gal4p can activate the
PUT
structural genes in a strain lacking Put3p. We also show that the activation of
PUT2
by Gal4p depends on the presence of the inducer galactose and the Put3p binding site and that activation increases with increased dosage of Gal4p. Put3p cannot activate the
GAL
genes in the absence of Gal4p. Our in vivo results confirm previously published in vitro data showing that Gal4p is more promiscuous than Put3p in its DNA binding ability. The results also suggest that under appropriate circumstances, Gal4p may be able to function in place of a related family member to activate expression.
Defining a
rob
Regulon in
Escherichia coli
by Using Transposon Mutagenesis
Authors: Bennik Marjon H. J. , Pomposiello Pablo J. , Thorne Derek F. , Demple Bruce 
Published: July 2002

ABSTRACT

The Rob protein of
Escherichia coli
is a member of the AraC-XylS family of prokaryotic transcriptional regulators and is expressed constitutively. Deletion of the
rob
gene increases susceptibility to organic solvents, while overexpression of Rob increases tolerance to organic solvents and resistance to a variety of antibiotics and to the superoxide-generating compound phenazine methosulfate. To determine whether constitutive levels of Rob regulate basal gene expression, we performed a MudJ transposon screen in a
rob
deletion mutant containing a plasmid that allows for controlled
rob
gene expression. We identified eight genes and confirmed that seven are transcriptionally activated by normal expression of Rob from the chromosomal
rob
gene (
inaA
,
marR
,
aslB
,
ybaO
,
mdlA
,
yfhD
, and
ybiS
). One gene,
galT
, was repressed by Rob. We also demonstrated by Northern analysis that basal expression of
micF
is significantly higher in wild-type
E. coli
than in a
rob
deletion mutant. Rob binding to the promoter regions of most of these genes was substantiated in electrophoretic mobility shift assays. However, Mu insertions in individual Rob-regulated genes did not affect solvent sensitivity. This phenotype may depend on changes in the expression of several of these Rob-regulated genes or on other genes that were not identified. Rob clearly affects the basal expression of genes with a broad range of functions, including antibiotic resistance, acid adaptation, carbon metabolism, cell wall synthesis, central intermediary metabolism, and transport. The magnitudes of Rob's effects are modest, however, and the protein may thus play a role as a general transcription cofactor.