bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective Early Production of CCL20, or Macrophage Inflammatory Protein 3α, by Human Mast Cells in Response toPseudomonas aeruginosa
Authors: Lin Tong-Jun , Maher Lauren H. , Gomi Kaede , McCurdy Jeffrey D. , Garduno Rafael , Marshall Jean S. 
Published: December 2002

ABSTRACTMast cells are important as sentinel cells in host defense against bacterial infection. Much of their effectiveness depends upon recruiting other immune cells; however, little is known about the mechanisms of this response. CCL20, also known as macrophage inflammatory protein-3α (MIP-3α), Exodus, and LARC, is a chemokine known to be a potent chemoattractant for immature dendritic cells and T cells. In this study, we examined the human mast cell production of both CCL20 and granulocyte-macrophage colony-stimulating factor (GM-CSF), a critical cytokine for innate immune responses in the lung, in response toPseudomonas aeruginosa. Reverse transcription-PCR and Western blot analysis demonstrated that the human mast cells (HMC-1) express CCL20 mRNA and are able to produce a significant amount (32.4 ng/ml) of CCL20 protein following stimulation by calcium ionophore and phorbol myristate acetate. Importantly,P. aeruginosapotently stimulated CCL20 production in human cord blood-derived mast cells (CBMC), with production peaking at 6 h after stimulation. This time course of expression was distinct from that of GM-CSF, which peaked after 24 to 48 h. Significant CCL20 production did not occur following immunoglobulin E-mediated activation of CBMC under conditions which induced a substantial GM-CSF response. Interestingly, the CCL20 response of mast cells toP. aeruginosawas relatively resistant to inhibition by the corticosteroid dexamethasone, interleukin-10, or cyclosporine, while GM-CSF production was potently inhibited. However,P. aeruginosa-induced CCL20 production was blocked by the protein kinase C (PKC) inhibitor Ro 31-8220 and a PKC pseudosubstrate. These results support a role for human mast cells in the initiation of immune responses toP. aeruginosainfection.
The
Salmonella enterica
Serovar Typhimurium Translocated Effectors SseJ and SifB Are Targeted to the
Salmonella
-Containing Vacuole
Authors: Freeman Jeremy A. , Ohl Michael E. , Miller Samuel I. 
Published: December 2002

ABSTRACT

The
Salmonella enterica
serovar Typhimurium type III secretion system (TTSS) encoded in
Salmonella
pathogenicity island 2 (SPI-2) promotes replication within host cells and systemic infection of mice. The SPI-2 TTSS is expressed following
Salmonella
internalization into host cells and translocates effectors across the membrane of the
Salmonella
-containing vacuole (SCV). Two effectors with similar amino-terminal domains, SseJ and SifB, localize to the SCV membrane in infected HEp-2 cells and subsequently traffic away from the SCV along
Salmonella-
induced-filaments (Sifs). Following infection of RAW cells, SseJ and SifB localize to the SCV as well as LAMP-1-positive, vesicular-appearing structures distant from the SCV. Trafficking of SseJ and SifB away from the SCV requires the SPI-2 effector SifA. Deletion of
sseJ
, but not
sifB
, leads to attenuation of
Salmonella
replication in mice following intraperitoneal inoculation. The contribution of SseJ to in vivo replication is identical in wild-type and
sifA
deletion backgrounds, suggesting that SseJ trafficking away from the SCV along Sifs is unnecessary for its virulence function.
Divergent Patterns of Colonization and Immune Response Elicited from Two IntestinalLactobacillusStrains That Display Similar Properties In Vitro
Authors: Ibnou-Zekri Nabila , Blum Stephanie , Schiffrin Eduardo J. , von der Weid Thierry 
Published: December 2002

ABSTRACTLactobacilli derived from the endogenous flora of normal donors are being increasingly used as probiotics in functional foods and as vaccine carriers. However, a variety of studies done with distinct strains of lactobacilli has suggested heterogeneous and strain-specific effects. To dissect this heterogeneity at the immunological level, we selected two strains of lactobacilli that displayed similar properties in vitro and studied their impact on mucosal and systemic B-cell responses in monoxenic mice. Germfree mice were colonized withLactobacillus johnsonii(NCC 533) orLactobacillus paracasei(NCC 2461). Bacterial loads were monitored for 30 days in intestinal tissues, and mucosal and systemic B-cell responses were measured. Although bothLactobacillusstrains displayed similar growth, survival, and adherence properties in vitro, they colonized the intestinal lumen and translocated into mucosal lymphoid organs at different densities.L. johnsoniicolonized the intestine very efficiently at high levels, whereas the number ofL. paracaseidecreased rapidly and it colonized at low levels. We determined whether this difference in colonization correlated with an induction of different types of immune responses. We observed that colonization with either strain induced similar germinal center formation and immunoglobulin A-bearing lymphocytes in the mucosa, suggesting that both strains were able to activate mucosal B-cell responses. However, clear differences in patterns of immunoglobulins were observed between the two strains in the mucosa and in the periphery. Therefore, despite similar in vitro probiotic properties, distinctLactobacillusstrains may colonize the gut differently and generate divergent immune responses.
Differential Cytokine Pattern in the Spleens and Livers of BALB/c Mice Infected withPenicillium marneffei: Protective Role of Gamma Interferon
Authors: Sisto Francesca , Miluzio Annarita , Leopardi Orazio , Mirra Maurizio , Boelaert Johan R. , Taramelli Donatella 
Published: December 2002

ABSTRACTPenicillium marneffeiis an intracellular opportunistic fungus causing invasive mycosis in AIDS patients. T cells and macrophages are important for protection in vivo. However, the role of T-cell cytokines in the immune response againstP. marneffeiis still unknown. We studied by semiquantitative reverse transcription-PCR and biological assays the patterns of expression of Th1 and Th2 cytokines in the organs of wild-type (wt) and gamma interferon (IFN-γ) knockout (GKO) mice infected intravenously withP. marneffeiconidia. At 3 × 105conidia/mouse, a self-limiting infection developed in wt BALB/c mice, whereas all GKO mice died at day 18 postinoculation. Splenic and hepatic granulomas were present in wt mice, whereas disorganized masses of macrophages and yeast cells were detected in GKO mice. The infection resolved faster in the spleens than in the livers of wt mice and was associated with the local expression of type 1 cytokines (high levels of interleukin-12 [IL-12] and IFN-γ) but not type 2 cytokines (low levels of IL-4 and IL-10). Conversely, both type 1 and type 2 cytokines were detected in the livers of wt animals. Disregulation of the cytokine profile was seen in the spleens but not in the livers of GKO mice. The inducible nitric oxide synthase mRNA level was low and the TNF-α level was high in both spleens and livers of GKO mice compared to wt mice. These data suggest that the polarization of a protective type 1 immune response againstP. marneffeiis regulated at the level of individual organs and that the absence of IFN-γ is crucial for the activation of fungicidal macrophages and the development of granulomas.
Diversity at the Locus Associated with Transcription of a Variable Surface Antigen ofPneumocystis cariniias an Index of Population Structure and Dynamics in Infected Rats
Authors: Keely Scott P. , Cushion Melanie T. , Stringer James R. 
Published: December 2002

ABSTRACTPneumocystis cariniiexpresses a surface glycoprotein called MSG. Different isoforms of MSG are encoded by a gene family spread over at least 15 telomeric sites. Only one locus, called UCS, supports the production of MSG mRNA. Previous studies showed thatP. cariniipopulations from individual rats exhibited high degrees of diversity with respect to the MSG genes attached to the UCS locus. This diversity could have been generated primarily in the rats studied. Alternatively, the rats may have been infected byP. cariniiorganisms that were already different at the UCS locus. To investigate this issue, we examined the UCS locus inP. cariniifrom rats that had been exposed to few of the microbes at a specified time, which produced a bottleneck in the microbial population. Some of the rats with bottlenecks producedP. cariniipopulations in which a single MSG sequence resided at the UCS locus in 80 to 90% of the organisms, showing thatP. cariniican proliferate within a rat without generating the very high levels of UCS diversity previously seen. From the degree of diversity observed in the bottlenecked populations, the maximum rate of switching appeared to be 0.01 event per generation. These data also suggest that the infectious dose is as low as one organism, that rats that share a cage readily infect each other, and that the doubling time ofP. cariniiin vivo is ∼3 days. In addition, we found that inoculation with 107P. cariniiorganisms from a population highly heterogeneous at the UCS locus reproduced this heterogeneity. By contrast, shifts in population structure occurred in rats given 104P. cariniiorganisms, suggesting that a small fraction of these proliferated.
Role of Avian Pathogenic
Escherichia coli
Virulence Factors in Bacterial Interaction with Chicken Heterophils and Macrophages
Authors: Mellata Melha , Dho-Moulin Maryvonne , Dozois Charles M. , Curtiss Roy , Lehoux Brigitte , Fairbrother John M. 
Published: December 2002

ABSTRACT

Avian pathogenic
Escherichia coli
(APEC) cause extraintestinal disease in avian species via respiratory tract infection. Virulence factors associated with APEC include type 1 and P fimbriae, curli, aerobactin, lipopolysaccharide (LPS), K1 capsular antigen, temperature-sensitive hemagglutinin (Tsh), and an uncharacterized pathogen-specific chromosomal region (the 0-min region). The role of these virulence factors in bacterial interaction with phagocytes was investigated by using mutants of three APEC strains, each belonging to one of the most predominant serogroups O1, O2, and O78. Bacterial cell interaction with avian phagocytes was tested with primary cultures of chicken heterophils and macrophages. The presence of type 1 fimbriae and, in contrast, the absence of P fimbriae, K1 capsule, O78 antigen, and the 0-min region promoted bacterial association with chicken heterophils and macrophages. The presence of type 1 and P fimbriae, O78 antigen, and the 0-min region seemed to protect bacteria against the bactericidal effect of phagocytes, especially heterophils. The tested virulence factors seemed to have a limited role in intracellular survival for up to 48 h in macrophages. Generally, opsonized and nonopsonized bacteria were eliminated to the same extent, but in some cases, unopsonized bacteria were eliminated to a greater extent than opsonized bacteria. These results confirm the important role of type 1 fimbriae in promotion of initial phagocytosis, but nevertheless indicate a role for type 1 fimbriae in the protection of bacteria from subsequent killing, at least in heterophils. The results also indicate a role for K1 capsule, O78 antigen, P fimbriae, and the 0-min region in initial avoidance of phagocytosis, but demonstrate an additional role for O78 antigen, P fimbriae, and the 0-min region in subsequent protection against the bactericidal effects of phagocytes after bacterial association has occurred.
The
Vibrio
Pathogenicity Island-Encoded Mop Protein Modulates the Pathogenesis and Reactogenicity of Epidemic
Vibrio cholerae
Authors: Zhang Dalin , Xu Zheng , Sun Weiyun , Karaolis David K. R. 
Published: December 2002

ABSTRACT

Epidemic
Vibrio cholerae
possess the VPI (
Vibrio
pathogenicity island) essential virulence gene cluster. The VPI is 41.2 kb in size and encodes 29 potential proteins, several of which have no known function. We show that the VPI-encoded Orf4 is a predicted 34-kDa periplasmic protein containing a zinc metalloprotease motif.
V. cholerae
seventh-pandemic (El Tor) strain N16961 carrying an
orf4
mutation showed no obvious difference relative to its parent in the production of cholera toxin and the toxin-coregulated pilus, motility, azocasein digestion, and colonization of infant mice. However, analysis of rabbit ileal loops revealed that the N16961
orf4
mutant is hypervirulent, causing increased serosal hemorrhage and reactogenicity compared to its parent. Histology revealed a widening of submucosa, with an increase in inflammatory cells, diffuse lymphatic vessel dilatation, edema, endothelial cell hypertrophy of blood vessels, blunting of villi, and lacteal dilatation with lymphocytes and polymorphonuclear leukocytes. The mutant could be complemented in vivo with an
orf4
gene on a plasmid but not with an
orf4
gene containing a site-directed mutation in the putative zinc metalloprotease motif. Although its mechanism of its action is being studied further, our results suggest that the Orf4 protein is a zinc metalloprotease that modulates the pathogenesis and reactogenicity of epidemic
V. cholerae
. Based on our findings, we name this VPI-encoded protein Mop (for modulation of pathogenesis).
Expression of Proinflammatory Cytokines and Receptors by Human Fallopian Tubes in Organ Culture following Challenge withNeisseria gonorrhoeae
Authors: Maisey Kevin , Nardocci Gino , Imarai Monica , Cardenas Hugo , Rios Miguel , Croxatto Horacio B. , Heckels John E. , Christodoulides Myron , Velasquez Luis A. 
Published: December 2002

ABSTRACTInfection of the Fallopian tubes (FT) byNeisseria gonorrhoeaecan lead to acute salpingitis, an inflammatory condition, which is a major cause of infertility. Challenge of explants of human FT with gonococci induced mRNA expression and protein secretion for the proinflammatory cytokines interleukin (IL)-1α, IL-1β, and tumor necrosis factor alpha (TNF-α) but not for granulocyte-macrophage colony-stimulating factor. In contrast, FT expression of IL-6 and of the cytokine receptors IL-6R, TNF receptor I (TNF-RI), and TNF-RII was constitutive and was not increased by gonococcal challenge. These studies suggest that several proinflammatory cytokines are likely to contribute to the cell and tissue damage observed in gonococcal salpingitis.
Vibrio vulnificus
Induces Macrophage Apoptosis In Vitro and In Vivo
Authors: Kashimoto Takashige , Ueno Shunji , Hanajima Miyuki , Hayashi Hisae , Akeda Yukihiro , Miyoshi Shinichi , Hongo Toshiharu , Honda Takeshi , Susa Nobuyuki 
Published: December 2002

ABSTRACT

In this study, we compared the apoptotic activities of clinical and environmental isolates of
Vibrio vulnificus
toward macrophages in vitro and in vivo. The clinical isolates induced apoptosis in macrophage-like cells in vitro and in macrophages in vivo. This suggests that macrophage apoptosis may be important for the clinical virulence of
V. vulnificus
.
Campylobacter jejuniCytolethal Distending Toxin Promotes DNA Repair Responses in Normal Human Cells
Authors: Hassane Duane C. , Lee Robert B. , Pickett Carol L. 
Published: December 2002

ABSTRACTCytolethal distending toxin (CDT) is a multisubunit protein found in various gram-negative bacterial pathogens of humans which is thought to cause cell death by direct DNA damage of host cells. We sought to determine if a cellular response to DNA damage could be detected by exogenous addition of the holotoxin. Exogenous addition of theCampylobacter jejuni81-176 CDT to primary human fibroblasts resulted in formation of Rad50 foci, which are formed around double-stranded-DNA breaks. Moreover, such foci are formed in both proliferating and nonproliferating cells that are treated withC. jejuniCDT. Fibroblasts that were intoxicated and later stimulated to proliferate failed to divide and remained arrested in the G1phase of the cell cycle.
OxyR Acts as a Repressor of Catalase Expression in
Neisseria gonorrhoeae
Authors: Tseng Hsing-Ju , McEwan Alastair G. , Apicella Michael A. , Jennings Michael P. 
Published: December 2002

ABSTRACT

It has been reported that
Neisseria gonorrhoeae
possesses a very high level of catalase activity, but the regulation of catalase expression has not been investigated extensively. In
Escherichia coli
and
Salmonella enterica
serovar Typhimurium, it has been demonstrated that OxyR is a positive regulator of hydrogen peroxide-inducible genes, including the gene encoding catalase. The
oxyR
gene from
N. gonorrhoeae
was cloned and used to complement an
E. coli oxyR
mutant, confirming its identity and function. The gene was inactivated by inserting a kanamycin resistance cassette and used to make a knockout allele on the chromosome of
N. gonorrhoeae
strain 1291. In contrast to
E. coli
, the
N. gonorrhoeae oxyR
::
kan
mutant expressed ninefold-more catalase activity and was more resistant to hydrogen peroxide killing than the wild type. These data are consistent with OxyR in
N. gonorrhoeae
acting as a repressor of catalase expression.
Feasibility of an HA2 Domain-Based Periodontitis Vaccine
Authors: DeCarlo A. A. , Huang Y. , Collyer C. A. , Langley D. B. , Katz J. 
Published: December 2002

ABSTRACT

In a rat periodontitis model, preinoculation with the
Porphyromonas gingivalis
HA2 binding domain for hemoglobin provided protection from disease. Protection was associated with induced anti-HA2 immunoglobulin G (IgG) humoral antibodies. The IgG subclass ratios suggested that relatively lower Th2/Th1-driven responses were directly associated with protection when rHA2 was administered in saline.
Induction of Emetic Response to Staphylococcal Enterotoxins in the House Musk Shrew (
Suncus murinus
)
Authors: Hu Dong-Liang , Omoe Katsuhiko , Shimoda Yu , Nakane Akio , Shinagawa Kunihiro 
Published: December 2002

ABSTRACT

The emetic responses induced by staphylococcal enterotoxin A (SEA), SEB, SEC2, SED, SEE, SEG, SEH, and SEI in the house musk shrew (
Suncus murinus
) were investigated. SEA, SEE, and SEI showed higher emetic activity in the house musk shrew than the other SEs. SEB, SEC2, SED, SEG, and SEH also induced emetic responses in this animal model but relatively high doses were required. The house musk shrew appears to be a valuable model for studying the mechanisms of emetic reactions caused by SEs.
A Single-Copy Gene Encodes Kex1, a Serine Endoprotease of
Pneumocystis jiroveci
Authors: Kutty Geetha , Kovacs Joseph A. 
Published: December 2002

ABSTRACT

We have cloned and characterized the
kex1
gene of
Pneumocystis jiroveci
. Unlike the case for
Pneumocystis carinii
, in which the homologous PRT-1 genes are multicopy,
kex1
is a single-copy gene encoding a protein homologous to fungal serine endoproteases, which localize to the Golgi apparatus. Thus, substantial biological differences can be seen among
Pneumocystis
species.
Antibodies Present in Normal Human Serum Inhibit Invasion of Human Brain Microvascular Endothelial Cells byListeria monocytogenes
Authors: Hertzig Tobias , Weber Martin , Greiffenberg Lars , Holthausen Britta Schulte , Goebel Werner , Kim Kwang Sik , Kuhn Michael 
Published: December 2002

ABSTRACTListeria monocytogenescauses meningitis and encephalitis in humans and crosses the blood-brain barrier by yet unknown mechanisms. The interaction of the bacteria with different types of endothelial cells was recently analyzed, and it was shown that invasion into, but not adhesion to, human brain microvascular endothelial cells (HBMEC) depends on the product of theinlBgene, the surface molecule InlB, which is a member of the internalin multigene family. In the present study we analyzed the role of the medium composition in the interaction ofL. monocytogeneswith HBMEC, and we show that invasion of HBMEC is strongly inhibited in the presence of adult human serum. The strong inhibitory activity, which is not present in fetal calf serum, does not inhibit uptake by macrophage-like J774 cells but does also inhibit invasion of Caco-2 epithelial cells. The inhibitory component of human serum was identified as being associated withL. monocytogenes-specific antibodies present in the human serum. Human newborn serum (cord serum) shows only a weak inhibitory activity on the invasion of HBMEC byL. monocytogenes.
Inactivation of the
selB
Gene in
Methanococcus maripaludis:
Effect on Synthesis of Selenoproteins and Their Sulfur-Containing Homologs
Authors: Rother Michael , Mathes Isabella , Lottspeich Friedrich , Böck August 
Published: December 2002

ABSTRACT

The genome of
Methanococcus maripaludis
harbors genes for at least six selenocysteine-containing proteins and also for homologs that contain a cysteine codon in the position of the UGA selenocysteine codon. To investigate the synthesis and function of both the Se and the S forms, a mutant with an inactivated
selB
gene was constructed and analyzed. The mutant was unable to synthesize any of the selenoproteins, thus proving that the gene product is the archaeal translation factor (aSelB) specialized for selenocysteine insertion. The wild-type form of
M. maripaludis
repressed the synthesis of the S forms of selenoproteins, i.e., the selenium-independent alternative system, in selenium-enriched medium, but the mutant did not. We concluded that free selenium is not involved in regulation but rather a successional compound such as selenocysteyl-tRNA or some selenoprotein. Apart from the S forms, several enzymes from the general methanogenic route were affected by selenium supplementation of the wild type or by the
selB
mutation. Although the growth of
M. maripaludis
on H
2
/CO
2
is only marginally affected by the
selB
lesion, the gene is indispensable for growth on formate because
M. maripaludis
possesses only a selenocysteine-containing formate dehydrogenase.
Global Role for ClpP-Containing Proteases in Stationary-Phase Adaptation of
Escherichia coli
Authors: Weichart Dieter , Querfurth Nadine , Dreger Mathias , Hengge-Aronis Regine 
Published: December 2002

ABSTRACT

To elucidate the involvement of proteolysis in the regulation of stationary-phase adaptation, the
clpA
,
clpX
, and
clpP
protease mutants of
Escherichia coli
were subjected to proteome analysis during growth and during carbon starvation. For most of the growth-phase-regulated proteins detected on our gels, the
clpA
,
clpX
, or
clpP
mutant failed to mount the growth-phase regulation found in the wild type. For example, in the
clpP
and
clpA
mutant cultures, the Dps protein, the WrbA protein, and the periplasmic lysine-arginine-ornithine binding protein ArgT did not display the induction typical for late-stationary-phase wild-type cells. On the other hand, in the protease mutants, a number of proteins accumulated to a higher degree than in the wild type, especially in late stationary phase. The proteins affected in this manner include the LeuA, TrxB, GdhA, GlnA, and MetK proteins and alkyl hydroperoxide reductase (AhpC). These proteins may be directly degraded by ClpAP or ClpXP, respectively, or their expression could be modulated by a protease-dependent mechanism. From our data we conclude that the levels of most major growth-phase-regulated proteins in
E. coli
are at some point controlled by the activity of at least one of the ClpP, ClpA, and ClpX proteins. Cultures of the strains lacking functional ClpP or ClpX also displayed a more rapid loss of viability during extended stationary phase than the wild type. Therefore, regulation by proteolysis seems to be more important, especially in resting cells, than previously suspected.