bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Transcriptional Response of Human Neutrophils toAnaplasma phagocytophilumInfection
Authors: Sukumaran Bindu , Carlyon Jason A. , Cai Ji-Lian , Berliner Nancy , Fikrig Erol
Published: November 2005

Anaplasma phagocytophilum, an unusual obligate intracellular pathogen that persists within neutrophils, causes human anaplasmosis (previously known as human granulocytic ehrlichiosis). To study the effects of this pathogen on the transcriptional profile of its host cell, we performed a comprehensive DNA microarray analysis of the early (4-h) transcriptional response of human neutrophils toA. phagocytophiluminfection.A. phagocytophiluminfection resulted in the up- and down-regulation of 177 and 67 neutrophil genes, respectively. These data were verified by quantitative reverse transcription-PCR of selected genes. Notably, the up-regulation of many antiapoptotic genes, including the BCL2A1, BIRC3, and CFLAR genes, and the down-regulation of the proapoptotic TNFSF10 gene were observed. Genes involved in inflammation, innate immunity, cytoskeletal remodeling, and vesicular transport also exhibited differential expression. Vascular endothelial growth factor was also induced. These data suggest thatA. phagocytophilummay alter selected host pathways in order to facilitate its survival within human neutrophils. To gain further insight into the bacterium's influence on host cell gene expression, this report presents a detailed comparative analysis of our data and other gene expression profiling studies ofA. phagocytophilum-infected neutrophils and promyelocytic cell lines.
Global Virulence Regulation in
Staphylococcus aureus
: Pinpointing the Roles of ClpP and ClpX in the
sar/agr
Regulatory Network
Authors: Frees Dorte , Sørensen Karen , Ingmer Hanne
Published: November 2005

Staphylococcus aureus
causes infections ranging from superficial wound infections to life-threatening systemic infections. Essential for
S. aureus
pathogenicity are a number of cell-wall-associated and secreted proteins that are controlled by a complex regulatory network involving the quorum-sensing
agr
locus and a large set of transcription factors belonging to the Sar family. Recently, we revealed a new layer of regulation by showing that mutants lacking the ClpXP protease produce reduced amounts of several extracellular virulence factors and that, independently of ClpP, ClpX is required for transcription of
spa
, encoding Protein A. Here we find that the independent effect of ClpX is not general for other cell wall proteins, as expression of fibronectin- and fibrinogen-binding proteins was increased in the absence of either ClpX or ClpP. To assess the roles of ClpX and ClpP within the
sar/agr
regulatory network, deletions in
clpX
and
clpP
were combined with mutations in these genes. Interestingly, the derepression of
spa
transcription normally observed in an
agr
-negative strain was abolished in cells devoid of ClpX, and apparently ClpX modulates both SarS-dependent and SarS-independent control of
spa
expression, perhaps through the Sar family member Rot. Examination of expression of a single secreted protein, the SspA serine protease, revealed that ClpXP, similar to
agr
, is required for growth phase-dependent transcriptional induction of
sspa
. Intriguingly, induction was restored by the concomitant inactivation of Rot. We hypothesize that RNAIII accumulating in the postexponential phase may target Rot for degradation by ClpXP, leading to derepression of
sspA
.
Epitope-Specific Regulation of Immunoglobulin Class Switching in Mice Immunized with Malarial Merozoite Surface Proteins
Authors: Tongren Jon Eric , Corran Patrick H. , Jarra William , Langhorne Jean , Riley Eleanor M.
Published: November 2005

Antibodies that bind to Fc receptors and activate complement are implicated in the efficient control of pathogens, but the processes that regulate their induction are still not well understood. To investigate antigen-dependent factors that regulate class switching, we have developed an in vivo model of class switching to immunoglobulin G2b (IgG2b) using the malaria antigenPlasmodium falciparummerozoite surface protein 2 (MSP2). C57BL/6 mice were immunized with recombinant proteins representing discrete domains of MSP2, and a T-cell epitope (C8) was identified within the conserved C terminus of the protein that preferentially induces IgG2b antibodies. The ability of C8 to induce IgG2b is ablated in both homozygous gamma interferon-negative and interleukin 10-negative mice. The IgG2b-inducing properties of C8 override the IgG1-inducing properties of both the fusion protein partner, glutathioneS-transferase, and the adjuvant. Furthermore, when attached to other proteins that normally induce IgG1 responses, C8 induces a switch to IgG2b secretion. This is the first description of a defined T-cell epitope that drives specific IgG2b subclass switching, and our data offer proof of the concept that chimeric vaccines incorporating specific T-cell “switch epitopes” might be used to enhance qualitative aspects of the antibody response.
Th2-Associated Local Reactions to the Acellular Diphtheria-Tetanus-Pertussis Vaccine in 4- to 6-Year-Old Children
Authors: Rowe Julie , Yerkovich Stephanie T. , Richmond Peter , Suriyaarachchi Devinda , Fisher Elizabeth , Feddema Leonie , Loh Richard , Sly Peter D. , Holt Patrick G.
Published: November 2005

Acellular vaccines against diphtheria-tetanus-pertussis (acellular pertussis) (DTaP) are being progressively introduced into vaccination programs worldwide, with the aim of reducing T-helper 1 (Th1)-associated reactogenicity associated with the cellular diphtheria-tetanus-pertussis (whole-cell pertussis) (DTwP) vaccine. The DTaP vaccine has an improved safety profile in infants, but little information is available concerning the nature of the ensuing immunological memory in older children and how this may affect the reactogenicity of DTaP booster doses. We have addressed this question in the present study by assessing polyclonal and vaccine antigen-specific humoral and cellular immune responses to boosting with DTaP in 4- to 6-year-old children primed during infancy with DTaP (n= 30) or DTwP (n= 16) and by correlating these parameters, in particular cytokine responses, with expression of local side effects at the injection site. Large local reactions (≥50-mm diameter) 24 to 72 h after receiving the DTaP booster occurred in 43% of exclusively DTaP-primed children, in contrast to 6% of children primed with DTwP. These reactions were associated with vigorous T helper 2 (Th2)-polarized memory responses to vaccine antigen exemplified by interleukin 5 (IL-5), IL-6, and IL-13 production and log-scale boosting of tetanus-specific immunoglobulin E and occurred most frequently among children who are intrinsically “high Th2 responders” as detected by in vitro responsiveness to polyclonal mitogen. Our findings suggest that priming during infancy with DTaP promotes stable, boostable Th2-polarized immunity against vaccine antigens, which in a significant subset of children is subsequently associated with local reactions at the booster site. The time course of these reactions suggests that the underlying mechanism involves reactivation of Th2-polarized cellular immune memory.
Vaccination with theChlamydia trachomatisMajor Outer Membrane Protein Can Elicit an Immune Response as Protective as That Resulting from Inoculation with Live Bacteria
Authors: Pal Sukumar , Peterson Ellena M. , de la Maza Luis M.
Published: November 2005

BALB/c mice were vaccinated by the intramuscular (i.m.) and subcutaneous (s.c.) routes with a native preparation of theChlamydia trachomatismouse pneumonitis (MoPn) major outer membrane protein (MOMP), using Montanide ISA 720 and CpG-1826 as adjuvants. A negative control group was immunized with ovalbumin and the two adjuvants, and a positive control group was immunized intranasally (i.n.) with 104inclusion-forming units (IFU) ofC. trachomatis. Four weeks after the last i.m.-plus-s.c. immunization, mice were challenged in the ovarian bursa with 105IFU ofC. trachomatisMoPn. Six weeks after the genital challenge, animals were mated, and the pregnancies were monitored. After vaccination with MOMP, the mice developed strongChlamydia-specific humoral and cellular immune responses. Following the genital challenge, of the mice vaccinated with the MOMP, only 15% (3/20) had positive vaginal cultures, while 85% (17/20) of the animals immunized with ovalbumin had positive cultures over the 6 weeks of observation (P< 0.05). Also, only 14% (3/21) of the animals inoculated i.n. withChlamydiahad positive vaginal cultures. After mating, 75% (15/20) of the mice vaccinated with MOMP carried embryos in both uterine horns. Of the animals vaccinated i.n. with theChlamydia, 81% (17/21) had embryos in both uterine horns (P> 0.05). In contrast, only 10% (2/20) of the mice immunized with ovalbumin had embryos in both uterine horns (P< 0.05). In conclusion, immunization with a purified preparation of the MOMP is as effective as vaccination with viableC. trachomatisin eliciting a protective immune response against a genital challenge in mice.
Ectophosphorylation of CD36 Regulates Cytoadherence of
Plasmodium falciparum
to Microvascular Endothelium under Flow Conditions
Authors: Ho May , Hoang Holly L. , Lee Kristine M. , Liu Naili , MacRae Tara , Montes Laura , Flatt Christine L. , Yipp Bryan G. , Berger Bradley J. , Looareesuwan Sorrnchai , Robbins Stephen M.
Published: November 2005

The adhesion of
Plasmodium falciparum
-infected erythrocytes (IRBCs) to human dermal microvascular endothelial cells (HDMECs) under flow conditions is regulated by a Src family kinase- and alkaline phosphatase (AP)-dependent mechanism. In this study, we showed that the target of the phosphatase activity is the ectodomain of CD36 at threonine-92 (Thr
92
). Mouse fibroblasts (NIH 3T3 cells) transfected with wild-type CD36 or a mutant protein in which Thr
92
was substituted by Ala supported the rolling and adhesion of IRBCs. However, while the Src family kinase inhibitors PP1 and PP2 and the specific AP inhibitor levamisole significantly reduced IRBC adhesion to wild-type CD36 transfectants as with HDMECs, the inhibitors had no effect on IRBC adhesion to the mutant cells. Using a phosphospecific antibody directed at a 12-amino-acid peptide spanning Thr
92
, we demonstrated directly that CD36 was constitutively phosphorylated and could be dephosphorylated by exogenous AP. Endothelial CD36 was likewise constitutively phosphorylated. The phosphospecific antibody inhibited IRBC adhesion to HDMECs that could be reversed by preincubating the antibody with the phosphorylated but not the nonphosphorylated peptide. Pretreatment of HDMECs with AP abrogated the effect of PP1 on IRBC adhesion. Collectively, these results are consistent with a critical role for CD36 dephosphorylation through Src family kinase activation in regulating IRBC adhesion to vascular endothelium.
Relative Roles of Complement Factor 3 and Mannose-Binding Lectin in Host Defense against Infection
Authors: Takahashi Kazue , Shi Lei , Gowda Lakshmi D. , Ezekowitz R. Alan B.
Published: November 2005

Staphylococcus aureusis a major cause of severe nosocomial and community-acquired infections. Phagocytes and humoral molecules, including complement, have been proposed to cooperate in host defense against gram-positive bacteria. Circumstantial evidence indicates a role for complement, but this has not been formally defined. Complement activation is initiated by the classical, alternative, or lectin pathway, with the latter requiring mannose-binding lectin (MBL, also known as mannose-binding protein). MBL is an oligomeric serum protein that recognizes carbohydrates decorating a broad range of infectious agents, includingS. aureus. We previously reported that MBL null mice were highly susceptible toS. aureusinfection, confirming that MBL plays a key role in first-line host defense. In this study, we evaluated the relative roles of C3 and MBL againstS. aureusinfection by generating MBL × C3 null mice to compare with C3 single null mice. C3 deficiency alone significantly reduced survival to 19% from 97% of wild-type mice (P< 0.0001). Surprisingly, an additional MBL deficiency reduced the survival further to 7% (P< 0.0001). However, the MBL deficiency alone had a smaller though significant effect on survival, which was 77% (P= 0.018 versus wild-type mice). These results confirm an essential function for complement in host resistance againstS. aureusinfection but also identify an MBL-dependent mechanism that is C3 independent.
Anaplasma phagocytophilumDelay of Neutrophil Apoptosis through the p38 Mitogen-Activated Protein Kinase Signal Pathway
Authors: Choi Kyoung-Seong , Park Joon Tae , Dumler J. Stephen
Published: November 2005

Human granulocytic anaplasmosis is caused by the obligate intracellular bacteriumAnaplasma phagocytophilum. The bacterium avoids host innate defenses in part by infecting, surviving in, and propagating in neutrophils, as well as by inhibiting neutrophil apoptosis. However, the mechanisms ofA. phagocytophilumsurvival in neutrophils and the inhibition of spontaneous apoptosis are not well understood. In this study, we demonstrated that antiapoptotic Mcl-1 protein (Bcl-2 family) expression is maintained and that inhibition of procaspase-3 processing occurs inA. phagocytophilum-infected human neutrophils. An evaluation of p38 mitogen-activated protein kinase (MAPK) showed evidence of increased phosphorylation with infection. Moreover, antagonism of p38 MAPK by the inhibitor SB203580 reversed apoptosis inhibition in live or heat-killedA. phagocytophilum-infected neutrophils. A role for the autocrine or paracrine production of antiapoptotic interleukin 8 (IL-8) expressed withA. phagocytophiluminfection was excluded by the use of IL-8-, IL-8R1 (CXCR1)-, and IL-8R2 (CXCR2)-blocking antibodies. As previously demonstrated, the antiapoptotic effect was initially mediated by exposure toA. phagocytophilumcomponents in heat-killed bacteria. However, an important role for active infection is demonstrated by the additional delay in apoptosis with intracellular growth and the refractory abrogation of this response by the p38 MAPK inhibitor 3 to 6 h after neutrophil infection. These results suggest that the initial activation of the p38 MAPK pathway leading toA. phagocytophilum-delayed neutrophil apoptosis is bypassed with active intracellular infection. Moreover, active intracellular infection contributes more to the overall delay in apoptosis than do components of heat-killedA. phagocytophilumalone.
Cryptococcus neoformans
Gene Involved in Mammalian Pathogenesis Identified by a
Caenorhabditis elegans
Progeny-Based Approach
Authors: Tang Robin J. , Breger Julia , Idnurm Alexander , Gerik Kimberly J. , Lodge Jennifer K. , Heitman Joseph , Calderwood Stephen B. , Mylonakis Eleftherios
Published: November 2005

Caenorhabditis elegans
can serve as a substitute host for the study of microbial pathogenesis. We found that mutations in genes of the fungal pathogen
Cryptococcus neoformans
involved in mammalian virulence allow
C. elegans
to produce greater numbers of progeny than when exposed to wild-type fungus. We used this property to screen a library of
C. neoformans
mutants for strains that permit larger
C. elegans
brood sizes. In this screen, we identified a gene homologous to
Saccharomyces cerevisiae ROM2. C. neoformans rom2
mutation resulted in a defect in mating and growth defects at elevated temperature or in the presence of cell wall or hyperosmolar stresses. An effect of the
C. neoformans rom2
mutation in virulence was confirmed in a murine inhalation infection model. We propose that a screen for progeny-permissive mutants of microorganisms can serve as a high-throughput method for identifying novel loci related to mammalian pathogenesis.
Roles of Specific Amino Acids in the N Terminus of
Pseudomonas aeruginosa
Flagellin and of Flagellin Glycosylation in the Innate Immune Response
Authors: Verma Amrisha , Arora Shiwani K. , Kuravi Sudha K. , Ramphal Reuben
Published: November 2005

The Toll-like receptor 5 (TLR5) binding site has been predicted to be in the N terminus of the flagellin molecule. In order to better define the interaction between the N-terminal amino acids of
Pseudomonas aeruginosa
flagellin and TLR5, site-specific mutations were generated between residues 88 and 97 of
P. aeruginosa
PAK flagellin as well as outside of this region. The mutant flagellins were expressed in
Escherichia coli
BL21(plysS), purified by affinity chromatography, and passed through a polymyxin B column to remove contaminating lipopolysaccharide (LPS). Their ability to stimulate interleukin-8 (IL-8) release from A549 cells was examined. The cloned mutated genes were used to complement a PAK
fliC
mutant in order to test for effects on motility and on IL-8 release by purified flagellar preparations. All the mutations, single or double, in the predicted TLR5 binding region reduced IL-8 signaling to less than 95% of the wild-type flagellin levels, but the single mutation outside the binding region had no effect. Changes made at two amino acid sites resulted in loss/reduction of motility; however, changes made at single sites, i.e., Q83A, L88A, R90A, M91A, L94A, and Q97A, had no effect on motility. The mutated genes encoding two of the motile but poorly signaling flagellins had no compensatory mutations to allow motility. Thus, while it is speculated that pathogen-associated molecular patterns (PAMPs) have evolved in locations that are essential to maintain function, it appears that there is tolerance for at least single amino acid changes in the PAMP of
P. aeruginosa
flagellin. The purpose of flagellin glycosylation in
P. aeruginosa
is unknown. In order to examine its role, if any, in signaling an inflammatory response, we used whole flagella from the motile chromosomal mutant strains PAK
rfbC
and PAO1
rfbC
, which are defective in flagellin glycosylation. IL-8 release from A549 cells stimulated with nonglycosylated flagellar preparations (having less then 1 picogram of LPS/μg) was significantly reduced compared to their respective wild-type flagellar preparations, indicating a role of flagellar glycosylation in the proinflammatory action of
Pseudomonas
flagellin. The basis of the latter activity is unknown, since the glycosylation sites are found in the D3 domain of flagellins and the TLR5 binding site is located in the D1 domain. Thus,
P. aeruginosa
flagellin has evolved additional flagellar signaling mechanisms over that described for
Salmonella
flagellin.
Induction of Protective Serum Meningococcal Bactericidal and Diphtheria-Neutralizing Antibodies and Mucosal Immunoglobulin A in Volunteers by Nasal Insufflations of theNeisseria meningitidisSerogroup C Polysaccharide-CRM197 Conjugate Vaccine Mixed with Chitosan
Authors: Huo Zhiming , Sinha Ruchi , McNeela Edel A. , Borrow Ray , Giemza Rafaela , Cosgrove Catherine , Heath Paul T. , Mills Kingston H. G. , Rappuoli Rino , Griffin George E. , Lewis David J. M.
Published: November 2005

Thirty-six healthy volunteers received either a single intramuscular injection ofNeisseria meningitidisserogroup C polysaccharide (MCP)-CRM197 conjugate vaccine in alum or two nasal insufflations 28 days apart of the same vaccine powder, without alum, mixed with chitosan. Nasal immunization was well tolerated, with fewer symptoms reported than after intramuscular injection. The geometric mean concentrations of MCP-specific immunoglobulin G (IgG) after one nasal immunization were 3.25 μg/ml in naïve subjects and 14.4 μg/ml in subjects previously immunized parenterally, compared with 4.30 μg/ml in naïve subjects immunized intramuscularly. The geometric mean titer of serum bactericidal antibody (SBA) rose 24-fold after two nasal immunizations in naïve subjects and was comparable to parenteral immunization (1,080 versus 1,625). All subjects achieved SBA titers associated with protection after two nasal immunizations: even those with titers of <8 at entry. A single nasal immunization boosted the SBA titer to ≥128 in 96% of previously immunized subjects, and two immunizations achieved this level in 92% of naive subjects. MCP-specific IgG levels were ∼70% IgG2 and ∼20% IgG1 after nasal or intramuscular immunization. Increases in CRM197-specific IgG and diphtheria toxin-neutralizing activity were observed after nasal or intramuscular immunization, with balanced IgG1/IgG2 and higher IgG4. Significant MCP-specific secretory IgA was detected in nasal wash only after nasal immunization and predominantly on the immunized side. Simple nasal insufflation of existing MCP-CRM197 conjugate vaccines in chitosan offers an inexpensive but effective needle-free prime and boost against serogroup CN. meningitidisand diphtheria.
NoncapsulatedKlebsiella pneumoniaeBearing Mannose-Containing O Antigens Is Rapidly Eradicated from Mouse Lung and Triggers Cytokine Production by Macrophages following Opsonization with Surfactant Protein D
Authors: Kostina Elena , Ofek Itzhak , Crouch Erika , Friedman Rotem , Sirota Lea , Klinger Gil , Sahly Hany , Keisari Yona
Published: November 2005

To better understand the relationship between the surface polysaccharides of pulmonary pathogens and components of the lung innate immune system, we employed selected serotypes ofKlebsiella pneumoniaeexpressing distinct capsular polysaccharides and/or O antigen in a murine model ofK. pneumoniaeinfection. In addition, we examined the effect of surfactant protein D (SP-D) on the cytokine response of human monocyte-derived macrophages to these serotypes in vitro. Noncapsulated mannose-containing O3 serotypes (K50/n and K55/n), which react efficiently with SP-D in vitro, triggered high levels of interleukin-1β (IL-1β) and IL-6 production. In vivo, they were more efficiently cleared from the lungs of mice but not from macrophage-depleted mice. They also were more efficiently internalized by alveolar macrophages in vivo. In contrast, galactose-containing O1 serotypes (K2/n and K21a/n), which interact poorly with SP-D, exhibited significantly lower cytokine production and less efficient pulmonary clearance and were ineffectively internalized by alveolar macrophages. These findings are consistent with in vitro results showing that production of IL-1β and IL-6 mRNA and IL-6 protein by human macrophages exposed to mannose-bearingKlebsiellaO serotypes is significantly increased by SP-D. Thus, survival of inhaled bacteria in the lung depends partially on the lipopolysaccharide structure of the bacteria and their interactions with innate immunity components. We speculate that an imbalance of host SP-D and therefore cytokine levels may result in high susceptibility of the host to the pathogen.
Protective Immunity to the Larval Stages ofOnchocerca volvulusIs Dependent on Toll-Like Receptor 4
Authors: Kerepesi Laura A. , Leon Ofra , Lustigman Sarah , Abraham David
Published: November 2005

Toll-like receptor 4 (TLR4) has been shown to be important for the induction of Th2-dependent immune responses in mice. Protective immunity against larvalOnchocerca volvulusin mice depends on the development of a Th2 immune response mediated by both interleukin-4 (IL-4) and IL-5. In addition,O. volvuluscontains the rickettsial endosymbiontWolbachia, which has molecules with lipopolysaccharide-like activities that also signal through TLR4. We therefore hypothesized that protective immunity toO. volvuluswould not develop in C3H/HeJ mice which have a mutation in theTlr4gene (TLR4 mutant), either because of a decreased Th2 response to the larvae or because of the absence of a response toWolbachia.TLR4-mutant mice were immunized againstO. volvuluswith irradiated third-stage larvae, and it was observed that Th2 responses were elevated based on increased IL-5 production, total immunoglobulin E (IgE) levels, antigen-specific IgG1 response, and eosinophil recruitment. Protective immunity, however, did not develop in the TLR4-mutant mice. The Th1 response, as measured by gamma interferon production from spleen cells, was comparable in both wild-type and TLR4-mutant mice. Furthermore, antibody responses toWolbachiawere absent in both wild-type and TLR4-mutant mice. Therefore, the defect in the development of a protective immune response againstO. volvulusin TLR4-mutant mice is not due to loss of Th2 immunity or the response toWolbachiabut is due to an unidentified TLR4-dependent larval killing mechanism.
Shiga Toxin 2 and Lipopolysaccharide Induce Human Microvascular Endothelial Cells To Release Chemokines and Factors That Stimulate Platelet Function
Authors: Guessous Fadila , Marcinkiewicz Marek , Polanowska-Grabowska Renata , Kongkhum Sudawadee , Heatherly Daniel , Obrig Tom , Gear Adrian R. L.
Published: November 2005

Shiga toxins (Stxs) produced by
Shigella dysenteriae
type 1 and enterohemorrhagic
Escherichia coli
are the most common cause of hemolytic-uremic syndrome (HUS). It is well established that vascular endothelial cells, mainly those located in the renal microvasculature, are targets for Stxs. The aim of the present research was to evaluate whether
E. coli
-derived Shiga toxin 2 (Stx2) incubated with human microvascular endothelial cells (HMEC-1) induces release of chemokines and other factors that might stimulate platelet function. HMEC-1 were exposed for 24 h in vitro to Stx2, lipopolysaccharide (LPS), or the Stx2-LPS combination, and chemokine production was assessed by immunoassay. More interleukin-8 was released than stromal cell-derived factor 1α (SDF-1α) or SDF-1β and RANTES. The Stx2-LPS combination potentiated chemokine release, but Stx2 alone caused more release of SDF-1α at 24 h than LPS or Stx2-LPS did. In the presence of low ADP levels, HMEC-1 supernatants activated platelet function assessed by classical aggregometry, single-particle counting, granule secretion, P-selectin exposure, and the formation of platelet-monocyte aggregates. Supernatants from HMEC-1 exposed only to Stx2 exhibited enhanced exposure of platelet P-selectin and platelet-THP-1 cell interactions. Blockade of platelet cyclooxygenase by indomethacin prevented functional activation. The chemokine RANTES enhanced platelet aggregation induced by SDF-1α, macrophage-derived chemokine, or thymus and activation-regulated chemokine in the presence of very low ADP levels. These data support the hypothesis that microvascular endothelial cells exposed to
E. coli
O157:H7-derived Stx2 and LPS release chemokines and other factors, which when combined with low levels of primary agonists, such as ADP, cause platelet activation and promote the renal thrombosis associated with HUS.
Specific-Pathogen-Free Pigs as an Animal Model for Studying
Chlamydia trachomatis
Genital Infection
Authors: Vanrompay Daisy , Hoang Thi Q. T. , De Vos Liselotte , Verminnen Kristel , Harkinezhad Taher , Chiers Koen , Morré Servaas A. , Cox Eric
Published: November 2005

The purpose of the present study was to evaluate pigs as a large-animal model for female genital infection with two
Chlamydia trachomatis
human serovar E strains. Sixteen-week-old specific-pathogen-free female pigs (gilts) were intravaginally infected with the trachoma type E reference strain Bour or the urogenital serovar E strain 468. Several conclusions can be drawn from our findings on the pathogenicity of a primary
C. trachomatis
genital infection in gilts. First of all, we demonstrated that the serovar E strains Bour and 468 could ascend in the genital tract of gilts. The serovar E strains could replicate in the superficial columnar cervical epithelium and in the superficial epithelial layer of the uterus, which are known to be the specific target sites for a
C. trachomatis
genital infection in women. Second, inflammation and pathology occurred at the replication sites. Third, the organisms could trigger a humoral immune response, as demonstrated by the presence of immunoglobulin M (IgM), IgG, and IgA in both serum and genital secretion samples. Our findings imply that the pig model might be useful for studying the pathology, pathogenesis, and immune response to a
C. trachomatis
infection of the genital system.
Leishmania pifanoiAmastigotes Avoid Macrophage Production of Superoxide by Inducing Heme Degradation
Authors: Pham Nam-Kha , Mouriz Jennifer , Kima Peter E.
Published: November 2005

Whereas infections of macrophages by promastigote forms ofLeishmania mexicana pifanoiinduce the production of superoxide, infections by amastigotes barely induce superoxide production. Several approaches were employed to gain insight into the mechanism by which amastigotes avoid eliciting superoxide production. First, in experiments with nitroblue tetrazolium, we found that 25% of parasitophorous vacuoles (PVs) that harbor promastigotes are positive for the NADPH oxidase complex, in contrast to only 2% of PVs that harbor amastigotes. Second, confocal microscope analyses of infected cells labeled with antibodies to gp91phoxrevealed that this enzyme subunit is found in PVs that harbor amastigotes. Third, in immunoblots of subcellular fractions enriched with PVs from amastigote-infected cells and probed with antibodies to gp91phox, only the 65-kDa premature form of gp91phoxwas found. In contrast, subcellular fractions from macrophages that ingested zymosan particles contained both the 91- and 65-kDa forms of gp91phox. This suggested that only the immature form of gp91phoxis recruited to PVs that harbor amastigotes. Given that gp91phoxmaturation is dependent on the availability of heme, we found that infections byLeishmaniaparasites induce an increase in heme oxygenase 1 (HO-1), the rate-limiting enzyme in heme degradation. Infections by amastigotes performed in the presence of metalloporphyrins, which are inhibitors of HO-1, resulted in superoxide production by infected macrophages. Taken together, we propose thatLeishmaniaamastigotes avoid superoxide production by inducing an increase in heme degradation, which results in blockage of the maturation of gp91phox, which prevents assembly of the NADPH oxidase enzyme complex.
Regulation of Impaired Protein Kinase C Signaling by Chemokines in Murine Macrophages during Visceral Leishmaniasis
Authors: Dey Ranadhir , Sarkar Arup , Majumder Nivedita , Bhattacharyya (Majumdar) Suchandra , Roychoudhury Kaushik , Bhattacharyya Sandip , Roy Syamal , Majumdar Subrata
Published: November 2005

The protein kinase C (PKC) family regulates macrophage function involved in host defense against infection. In the case ofLeishmania donovaniinfection, the impairment of PKC-mediated signaling is one of the crucial events for the establishment of parasite into the macrophages. Earlier reports established that C-C chemokines mediated protection against leishmaniasis via the generation of nitric oxide after 48 h. In this study, we investigated the role of MIP-1α and MCP-1 in the regulation of impaired PKC activity in the early hours (6 h) of infection. These chemokines restored Ca2+-dependent PKC activity and inhibited Ca2+-independent atypical PKC activity inL. donovani-infected macrophages under both in vivo and in vitro conditions. Pretreatment of macrophages with chemokines induced superoxide anion generation by activating NADPH oxidase components in infected cells. Chemokine administration in vitro induced the migration of infected macrophages and triggered the production of reactive oxygen species. In vivo treatment with chemokines significantly restricted the parasitic burden in livers as well as in spleens. Collectively, these results indicate a novel regulatory role of C-C chemokines in controlling the intracellular growth and multiplication ofL. donovani, thereby demonstrating the antileishmanial properties of C-C chemokines in the disease process.
A Mutant ofFrancisella tularensisStrain SCHU S4 Lacking the Ability To Express a 58-Kilodalton Protein Is Attenuated for Virulence and Is an Effective Live Vaccine
Authors: Twine Susan , Byström Mona , Chen Wangxue , Forsman Mats , Golovliov Igor , Johansson Anders , Kelly John , Lindgren Helena , Svensson Kerstin , Zingmark Carl , Conlan Wayne , Sjöstedt Anders
Published: November 2005

Francisella tularensissubsp.tularensis(type A) strain SCHU S4 is a prototypic strain of the pathogen that is highly virulent for humans and other mammals. Its intradermal (i.d.) 50% lethal dose (LD50) for mice is <10 CFU. We discovered a spontaneous mutant, designated FSC043, of SCHU S4 with an i.d. LD50of >108CFU. FSC043 effectively vaccinated mice against challenge with a highly virulent type A strain, and the protective efficacy was at least as good as that ofF. tularensisLVS, an empirically attenuated strain which has been used as an efficacious human vaccine. Comparative proteomics was used to identify two proteins of unknown function that were identified as defective in LVS and FSC043, and deletion mutants of SCHU S4 were created for each of the two encoding genes. One mutant, the ΔFTT0918 strain, failed to express a 58-kDa protein, had an i.d. LD50of ∼105CFU, and was found to be less capable than SCHU S4 of growing in peritoneal mouse macrophages. Mice that recovered from sublethal infection with the ΔFTT0918 mutant survived when challenged 2 months later with >100 LD50s of the highly virulent type A strain FSC033. This is the first report of the generation of defined mutants ofF. tularensissubsp.tularensisand their use as live vaccines.
Mycobacterium-Induced Potentiation of Type 1 Immune Responses and Protection against Malaria Are Host Specific
Authors: Page Kathleen R. , Jedlicka Anne E. , Fakheri Benjamin , Noland Gregory S. , Kesavan Anup K. , Scott Alan L. , Kumar Nirbhay , Manabe Yukari C.
Published: November 2005

Malaria and tuberculosis are endemic in many regions of the world, and coinfection with the two pathogens is common. In this study, we examined the effects of long- and short-term infection withMycobacterium tuberculosison the course of a lethal form of murine malaria in resistant (C57BL/6) and susceptible (BALB/c) mice. C57BL/6 mice coinfected withM. tuberculosisCDC1551 andPlasmodium yoelii17XL had a lower peak parasitemia and increased survival compared to mice infected withP. yoelii17XL alone. Splenic microarray analysis demonstrated potentiation of type 1 immune responses in coinfected C57BL/6 mice, which was especially prominent 5 days after infection withP. yoelii17XL. Splenocytes from coinfected C57BL/6 mice produced higher levels of gamma interferon (IFN-γ) and tumor necrosis factor alpha than splenocytes from mice infected with either pathogen alone. Interestingly, mycobacterium-induced protection against lethalP. yoeliiis mouse strain specific. BALB/c mice were significantly more susceptible than C57BL/6 mice to infection withP. yoelii17XL and were not protected against lethal malaria by coinfection withM. tuberculosis. In addition,M. tuberculosisdid not augment IFN-γ responses in BALB/c mice subsequently infected withP. yoelii17XL. These data indicate thatM. tuberculosis-induced potentiation of type 1 immune responses is associated with protection against lethal murine malaria.
Impaired Kupffer Cells in Highly Susceptible Mice Infected withTrypanosoma congolense
Authors: Shi Meiqing , Wei Guojian , Pan Wanling , Tabel Henry
Published: November 2005

In highly susceptible BALB/c mice infected withTrypanosoma congolense, the total number of Kupffer cells in the liver remains constant; however, their mean size increases fivefold towards the terminal stage. About 25% of Kupffer cells undergo apoptosis. We suggest that development of an impairment of the macrophage system might be a major mechanism for inefficient elimination of trypanosomes.
Toll-Like Receptor 2 Deficiency Delays Pneumococcal Phagocytosis and Impairs Oxidative Killing by Granulocytes
Authors: Letiembre Maryse , Echchannaoui Hakim , Bachmann Philipp , Ferracin Fabrizia , Nieto Concepción , Espinosa Manuel , Landmann Regine
Published: November 2005

Phagocytosis and killing of
Streptococcus pneumoniae
was compared in blood-derived wild-type (WT) and Toll-like receptor 2 (TLR2)-deficient (TLR2
−/−
) polymorphonuclear leukocytes (PMN). Phagocytosis of green fluorescent protein-transformed pneumococci was delayed in TLR2
−/−
PMN. These cells exhibited also a lower oxidative bactericidal activity against
S. pneumoniae
than WT PMN, suggesting that TLR2 modulates bacterial clearance in PMN.
Characterization of Two Non-Locus of Enterocyte Effacement-Encoded Type III-Translocated Effectors, NleC and NleD, in Attaching and Effacing Pathogens
Authors: Marchés Olivier , Wiles Siouxsie , Dziva Francis , La Ragione Roberto M. , Schüller Stephanie , Best Angus , Phillips Alan D. , Hartland Elizabeth L. , Woodward Martin J. , Stevens Mark P. , Frankel Gad
Published: November 2005

Intestinal colonization by enteropathogenic and enterohemorrhagic
Escherichia coli
requires the locus of enterocyte effacement-encoded type III secretion system. We report that NleC and NleD are translocated into host cells via this system. Deletion mutants induced attaching and effacing lesions in vitro, while infection of calves or lambs showed that neither gene was required for colonization.
An Early Intestinal Mucosal Source of Gamma Interferon Is Associated with Resistance to and Control ofCryptosporidium parvumInfection in Mice
Authors: Leav Brett A. , Yoshida Masaru , Rogers Kathleen , Cohen Seth , Godiwala Nihal , Blumberg Richard S. , Ward Honorine
Published: November 2005

Resistance to and control ofCryptosporidium parvuminfection in mice in the absence of adaptive immunity appears to be gamma interferon (IFN-γ) dependent. Using an IFN-γ-neutralizing antibody in a murine model, we demonstrated increased susceptibility to infection within 24 h. We correlated this early resistance and control with increased mucosal expression of IFN-γ and demonstrate that CD8+T-cell receptor αβ intestinal intraepithelial lymphocytes express and secrete this cytokine shortly after infection. The rapid kinetics of IFN-γ expression and secretion by naive CD8+T cells in response to a protozoan pathogen have not previously been demonstrated.
Receptor-Mediated Clearance ofCryptococcus neoformansCapsular Polysaccharide In Vivo
Authors: Yauch Lauren E. , Mansour Michael K. , Levitz Stuart M.
Published: November 2005

Cryptococcus neoformanscapsular glucuronoxylomannan (GXM) is shed during cryptococcosis and taken up by macrophages. The roles of the putative GXM receptors CD14, CD18, Toll-like receptor 2 (TLR2), and TLR4 in GXM clearance from serum and deposition in the liver and spleen in receptor-deficient mice were studied. While alterations in the kinetics of GXM redistribution were seen in the mutant mice, none of the receptors was absolutely required for serum clearance or hepatosplenic accumulation.
Attenuation ofSalmonella entericaSerovar Typhimurium by Altering Biological Functions of Murein Lipoprotein and Lipopolysaccharide
Authors: Fadl A. A. , Sha J. , Klimpel G. R. , Olano J. P. , Galindo C. L. , Chopra A. K.
Published: November 2005

We constructedSalmonella entericaserovar Typhimurium double-knockout mutants in which either the lipoprotein A (lppA) or the lipoprotein B (lppB) gene was deleted from anmsbB-negative background strain by marker exchange mutagenesis. These mutants were highly attenuated when tested with in vitro and in vivo models ofSalmonellapathogenesis.
Neutralization of Tumor Necrosis Factor Alpha Suppresses Antigen-Specific Type 1 Cytokine Responses and Reverses the Inhibition of Mycobacterial Survival in Cocultures of Immune Guinea Pig T Lymphocytes and Infected Macrophages
Authors: Cho Hyosun , McMurray David N.
Published: November 2005

Neutralization of tumor necrosis factor alpha (TNF-α) significantly down-regulated antigen-induced lymphoproliferation and the expression of interleukin-12 p40 and gamma interferon mRNA and enhanced the viability of intracellular attenuated and virulent mycobacteria in cocultures of immune T cells and macrophages obtained fromMycobacterium bovisBCG-vaccinated guinea pigs. This suggests the crucial role of TNF-α in the activation of a type 1 T-cell response againstMycobacterium tuberculosisinfection.
Yersinia enterocoliticaInvasin-Dependent and Invasin-Independent Mechanisms of Systemic Dissemination
Authors: Handley Scott A. , Newberry Rodney D. , Miller Virginia L.
Published: November 2005

We report here invasin-dependent and invasin-independent mechanisms in which the enteropathogenYersinia enterocoliticais able to disseminate from the lumen of the small intestine to the spleen. The invasin-dependent route is clearly discernible in mice devoid of intestinal Peyer's patches and mesenteric lymph nodes.
Prognostic factors for duration of sick leave in patients sick listed with acute low back pain: a systematic review of the literature
Authors: Steenstra I A , Verbeek J H , Heymans M W , Bongers P M
Published: November 2005

Background:The percentages of patients with acute low back pain (LBP) that go on to a chronic state varies between studies from 2% to 34%. In some of these cases low back pain leads to great costs.

Aims:To evaluate the evidence for prognostic factors for return to work among workers sick listed with acute LBP.

Methods:Systematic literature search with a quality assessment of studies, assessment of levels of evidence for all factors, and pooling of effect sizes.

Results:Inclusion of studies in the review was restricted to inception cohort studies of workers with LBP on sick leave for less than six weeks, with the outcome measured in absolute terms, relative terms, survival curve, or duration of sick leave. Of the studies, 18 publications (14 cohorts) fulfilled all inclusion criteria. One low quality study, four moderate quality studies, and nine high quality studies were identified; 79 prognostic factors were studied and grouped in eight categories for which the evidence was assessed.

Conclusions:Specific LBP, higher disability levels, older age, female gender, more social dysfunction and more social isolation, heavier work, and receiving higher compensation were identified as predictors for a longer duration of sick leave. A history of LBP, job satisfaction, educational level, marital status, number of dependants, smoking, working more than 8 hour shifts, occupation, and size of industry or company do not influence duration of sick leave due to LBP. Many different constructs were measured to identify psychosocial predictors of long term sick leave, which made it impossible to determine the role of these factors.
Does long term residency near industry have an impact on the body burden of polychlorinated dibenzo-p-dioxins, furans, and polychlorinated biphenyls in older women?
Authors: Pless-Mulloli T , Edwards R , Howel D , Wood R , Paepke O , Herrmann T
Published: November 2005

Background:For the retrospective study of environment and health linkages biomarkers of exposure are required. Polychlorinated dibenzo-dioxins and furans (PCDD/F) and polychlorinated biphenyls (PCBs) have been useful markers in some settings. This is the first study of PCDD/F body burden in a population based sample from the UK.

Aims and Methods:The authors aimed to investigate whether long term residents close to a heavy chemical industrial complex (Teesside, UK) had a higher body burden and distinct pattern of PCDD/F and PCBs. We measured current levels of PCDD/F and PCBs in a population based sample of older women (mean 64 years, range 42–79 years). Forty women were recruited, 20 living near (zone A: 0.1–2.7 km) and 20 distant (zone C: 5–40 km) from industry during 2000–03. The authors ascertained occupational exposure to lung carcinogens, residential history, consumption of local produce, breast feeding, diet, and height and weight.

Results:The mean body burden measured on lipid basis in ng/kg for the whole sample was: WHO-TEQ (PCDD/Fs): 29.9, 2378TCDD: 4.0, PCB 118:16200, PCB156: 13100. Body burdens were similar to others reported from industrialised countries, except that mean 2378TCDD was slightly higher. Mean ages, body mass index, and lifelong dietary patterns were similar in both zones. The authors found no significant difference in mean body burden levels between zones A and C before or after adjustment for covariates. All congener patterns were consistent with an urban background pattern, and there was no significant difference between congener compositions in the two zones. The TCDD body burden increased with age with accelerated increments above age 70.

Conclusion:Long term residency near heavy and chemical industry did not have an effect on women’s body burden of PCDD/Fs and PCBs on Teesside, UK. The body burden of PCDD/F and PCBs was not a suitable biomarker for chronic, non-occupational exposure to industrial air pollution.
Serum DDT, age at menarche, and abnormal menstrual cycle length
Authors: Ouyang F , Perry M J , Venners S A , Chen C , Wang B , Yang F , Fang Z , Zang T , Wang L , Xu X , Wang X
Published: November 2005

Background:Although dichlorodiphenyl trichloroethane (DDT) exposure is known to affect human endocrine function, few previous studies have investigated the effects of DDT exposure on age at menarche or menstrual cycle length.

Methods:A cross sectional study was conducted to study the effects of DDT exposure on age at menarche and menstrual cycle length among 466 newly married, nulliparous female Chinese textile workers aged 20–34 years enrolled between 1996 and 1998. Serum was analysed for DDT and its major metabolites. Multivariate linear regression was used to estimate DDT exposure effects on age at menarche and multivariate logistic regression was used to estimate DDT exposure effects on odds of experiencing short or long cycles.

Results:Relative to those in the lowest DDT quartile, the adjusted mean age at menarche was younger in those in the fourth quartile (−1.11 years). Modeled as a continuous variable, a 10 ng/g increase in serum DDT concentration was associated with an adjusted reduction in age at menarche of 0.20 years. Relative to those in the lowest DDT quartile, odds of any short cycle (<21 days) in the previous year were higher for those in the fourth quartile (odds ratio = 2.78; 95% CI 1.07 to 7.14). There were no associations between serum DDT concentrations and odds of experiencing a long cycle (>40 days).

Conclusion:Results suggest that DDT exposure was associated with earlier age at menarche and increased risk of experiencing a shortened menstrual cycle.
Prolonged standing at work and hospitalisation due to varicose veins: a 12 year prospective study of the Danish population: Table 1
Authors: Tüchsen F , Hannerz H , Burr H , Krause N
Published: November 2005

Background:Recent studies suggest that prolonged standing at work is associated with the development of diseases of varicose veins (VV).

Aims:To assess the risk of hospitalisation due to VV in the lower extremities prospectively in workers standing or walking at least 75% of their time at work.

Methods:A representative random sample of 9653 working age adults was drawn from the Central Population Register of Denmark in 1991. Of these, 8664 accepted to be interviewed by telephone (response rate 90%). Respondents (2939 men and 2708 women) were 20–59 years old and employed in 1990. Risk ratios for VV were estimated by log-linear Poisson regression models separately for men and women with adjustment for smoking status, body mass index (BMI), heavy lifting, and, for females only, number of children at baseline.

Results:During 12 years of follow up, 40 hospitalisations due to VV were observed among the men and 71 among the women. For employees with jobs that require prolonged standing or walking compared to all other employees, the relative risk was 1.75 (95% CI 0.92 to 3.34) for men and 1.82 (95% CI 1.12 to 2.95) for women. The pooled estimate of the relative risk was 1.78 (95% CI 1.19 to 2.68). The aetiological fraction of prolonged standing or walking at work was estimated as 22.5% for men and 22.6% for women.

Conclusions:This prospective study confirms that prolonged standing at work constitutes an excess risk of hospital treatment due to varicose veins and accounts for more than one fifth of all cases of working age.