Human immunodeficiency virus 1 favors the persistence of infection by activating macrophages through TNF

Macrophages play a major role in HIV-1 persistence. In the present paper, we demonstrate that the absence of apoptosis in HIV-1-infected primary human monocyte-differentiated macrophages (MDM) correlates with an increase in anti-apoptotic (Bcl-2 and Bcl-x(L)) and a decrease in pro-apoptotic (Bax and Bad) proteins. This is associated with macrophage activation as shown by tumor necrosis factor (TNF) production and NF-kappaB activation upon infection. TNF production was shown to be involved in the upregulation of Bcl-2 and Bcl-x(L) because this increase was abolished by an anti-TNF anti-serum or an inhibitor of TNF synthesis. In parallel, inhibition of TNF production induced an increase in the number of apoptotic cells. Furthermore, using an inhibitor of NF-kappaB activation, we demonstrated that TNF-induced upregulation of Bcl-x(L) and Bcl-2 occurs, respectively, through a NF-kappaB-dependent and an NF-kappaB-independent pathway.     

Jumping translocations in multiple myeloma

Jumping translocations (JT) have been defined as nonreciprocal translocations involving a same donor chromosome arm or chromosome segment onto two or more recipient chromosomes in different cell lines in the same patient, leading to a mosaic karyotype. This definition has been expanded to also include extra copies of a same donor segment on different recipient chromosomes in a single clone. Six patients with multiple myeloma and JT involving chromosome arm 1q were identified among 37 patients presenting with chromosome 1 abnormalities. All six patients had an advanced disease and a short survival. The literature review allowed us to identify 24 additional patients with JT. Chromosomes 16 and 19 were the recipients in 11 (45.8%) and 6 (25%) of these 24 patients, respectively. Breakpoints on the recipient chromosomes were pericentromeric in 46.2% and telomeric in 40.4% of the breakpoints recorded. Since telomeres are made of (TTAGGG)n tandem DNA repeats that are also found in the pericentromeric heterochromatic regions (interstital telomeric sequences), it is presumed that jumping translocations arise through illegimate recombination between telomere repeat sequences and interstitial telomeric sequences.     

Bordetella pertussis Filamentous Hemagglutinin Enhances the Immunogenicity of Liposome-Delivered Antigen Administered Intranasally

In an attempt to increase the immunogenicity of mucosally delivered antigens, we incorporated the Bordetella pertussis filamentous hemagglutinin (FHA) adhesin into liposomes containing the glutathione S-transferase of Schistosoma mansoni (Sm28GST) as a model antigen. Outbred mice immunized twice intranasally with liposomes containing a constant suboptimal dose of Sm28GST and increasing doses of FHA produced anti-Sm28GST antibodies in a FHA dose-dependent manner. The addition of 3 μg of FHA to the liposomes induced more than 10-fold-higher anti-Sm28GST antibody titers, compared to those induced by liposomes without FHA. The presence of FHA did not alter the nature of the humoral immune response, and the sera contained anti-Sm28GST immunoglobulin G1 (IgG1), IgG2a, and IgG2b. However, anti-Sm28GST IgA was only detected when at least 3 μg of FHA was added to the preparation. These results show a promising potential for FHA to enhance the immunogenicity of mucosally administered antigens incorporated into liposomes.     

Contribution of the twin arginine translocation system to the virulence of enterohemorrhagic Escherichia coli O157:H7

Shiga toxin-producing Escherichia coli O157:H7 is a major food-borne infectious pathogen. In order to analyze the contribution of the twin arginine translocation (TAT) system to the virulence of E. coli O157:H7, we deleted the tatABC genes of the O157:H7 EDL933 reference strain. The mutant displayed attenuated toxicity on Vero cells and completely lost motility on soft agar plates. Further analyses revealed that the ΔtatABC mutation impaired the secretion of the Shiga toxin 1 (Stx1) and abolished the synthesis of H7 flagellin, which are two major known virulence factors of enterohemorrhagic E. coli O157:H7. Expression of the EDL933 stxAB₁ genes in E. coli K-12 conferred verotoxicity on this nonpathogenic strain. Remarkably, cytotoxicity assay and immunoblot analysis showed, for the first time, an accumulation of the holotoxin complex in the periplasm of the wild-type strain and that a much smaller amount of StxA₁ and reduced verotoxicity were detected in the ΔtatC mutant cells. Together, these results establish that the TAT system of E. coli O157:H7 is an important virulence determinant of this enterohemorrhagic pathogen.     

Study of genotypes and virB4 secretion gene of Bartonella henselae strains from patients with clinically defined cat scratch disease

Bartonella henselae is the causative agent of cat scratch disease (CSD), which usually presents as a self-limiting lymphadenopathy. Occasionally, the bacteria will spread and be responsible for tissue and visceral involvement. Two B. henselae genotypes (genotypes I and II) have been described to be responsible for uncomplicated CSD on the basis of 16S rRNA sequence analysis. A type IV secretion system (T4SS) similar to the virulence-associated VirB system of Agrobacterium tumefaciens was recently identified in the B. henselae Houston-1 genotype I strain. We studied the correlations of the B. henselae genotypes with the clinical presentations and with the presence of T4SS. Isolates originated from CSD patients whose lymph nodes were prospectively analyzed. B. henselae genotype I was identified in 13 of 42 patients (30%). Among these, two teenage twins presented with hepatosplenic CSD and one immunocompetent adult presented with osteomyelitis. Genotype II was detected in 28 of 42 patients (67%), all of whom presented with uncomplicated CSD. The last patient was infected with both genotypes. T4SS was studied by PCR amplification of the virB4 gene. Amplification of virB4 codons 146 to 256, 273 to 357, and 480 to 537 enabled us to detect 66, 90, and 100% of the B. henselae isolates, respectively. Sequence analysis revealed sequence variations that correlated with genotype distribution. Our studies suggest that B. henselae genotype I strains harbor virB4 genes that are different from those harbored by genotype II strains and that genotype I strains might be more pathogenic.     

Outer membrane protein A renders dendritic cells and macrophages responsive to CCL21 and triggers dendritic cell migration to secondary lymphoid organs

Outer membrane protein A (OmpA) is a class of bacterial cell wall protein that is immunogenic without adjuvant. As specific immune responses are initiated in the lymph nodes (LN, we analyzed the effect of the OmpA from Klebsiella pneumoniae (KpOmpA) onchemokine/ chemokine receptor expression by APC and on cell migration to the LN. Upon contact with KpOmpA, human immature DC and macrophages acquire CCR7 expression and responsiveness to CCL21. In parallel, CCR1 and CCR5 expression is down-regulated and CXCL8, CCL2, CCL3 and CCL5 production is up-regulated. Mice injected subcutaneously with KpOmpA present a transient inflammatory reaction at the site of injection accompanied by an enlargement of the draining LN with a higher proportion of DC and macrophages. Lastly, when exposed to KpOmpA prior injection, DC but not macrophages migrate to the draining LN. In conclusion, KpOmpA confers a migratory phenotype to DC and triggers their migration to the regional LN. This property contributes to explain how innate cells initiate adaptive immune response upon recognition of conserved bacterial components and also why OmpA is immunogenic in the absence of adjuvant.     

SGK1, a potential regulator of <Emphasis Type="Italic">c-fms</Emphasis> related breast cancer aggressiveness

The aggressive behavior of breast cancer cells can at times be modulated by hormonal mechanisms. Exposure to glucocorticoids (GC) has been shown to stimulate the invasiveness, motility and adhesiveness of breast cancer cells containing the glucocorticoid receptor. This is largely explained by GC-associated overexpression of the c-fms proto-oncogene, which encodes the receptor for the colony stimulating factor-1 (CSF-1). Our objective is to investigate additional GC-associated genetic alterations that could modulate c-fms related malignant behavior in breast cancer cells. A microarray technique using an oligonucleotide array representing 16,700 known expressed human genes was used to analyze the gene expression profile of breast cancer cells exposed to dexamethasone (Dex) or vehicle. Results were confirmed by western blot analysis. Six genes were found to be consistently differentially overexpressed in the Dex-exposed cells compared to control. We focused on serum-glucose kinase 1 (SGK1), a serine-threonine kinase known to be involved in intracellular signal transduction pathways and induced by GC and serum. An adhesion assay was performed on extracellular matrix after exposing the breast cancer cells to Dex, CSF-1 or to Dex or CSF-1 plus LY294002, a functional inhibitor of SGK1 action. Exposure to LY294002 significantly decreased both CSF-1 and Dex-induced adhesiveness to the level of control cells. SGK1 may act as a downstream intracellular regulator of c-fms, particularly of c-fms-induced adhesiveness of breast cancer cells after exposure to GC or CSF-1. This finding may have implications for potential therapeutic interventions aimed at decreasing the aggressiveness of breast cancer cells. This revised version was published online in July 2006 with corrections to the Cover Date.     

Persistence of colonization of intestinal mucosa by a probiotic strain,Lactobacillus casei subsp. rhamnosus Lcr35, after oral consumption

The colonization by the probiotic Lactobacillus casei subsp. rhamnosus Lcr35 of the gastrointestinal tracts of mice and humans was studied. The mice were orally given 10(9) CFU of Lcr35 either once or three times at 24-h intervals. A 16S ribosomal nucleic probe used in hybridization assays detected Lcr35 in the feces of mice for up to 3 days after the feeding, at a level of 10(8) to 10(9) CFU/g of feces. In the human assay, 12 healthy volunteers were enrolled in a randomized trial and ingested Lcr35 at a dosage of 10(8) or 10(10) or 10(12) CFU every day for 7 days. Then, after a 3-week posttreatment period, there was a second intake period similar to the first one. Analysis of fecal samples showed significant increases in the number of lactobacilli during the first intake period, whatever the dose given. The greatest increases were observed in subjects harboring the lowest indigenous population of Lcr35-like bacteria. During the 3-week posttreatment period, the number of CFU slightly decreased over time, and an increase, although not a statistically significant one, was observed during the second test period. These findings suggest that Lcr35 is able to survive within the gastrointestinal tract.     

Low molecular weight poly(imide-amide)s obtained by copolycondensation of 4,4′-methylenedi(phenyl isocyanate), trimellitic anhydride and benzoic acid in N-methyl-2-pyrrolidone, 3. Absolute number-average molecular weights and glass transition temperatures

In depth study of low molecular weight poly(imide-amide)s (PIA) obtained by copolycondensation of 4,4′-methylenedi(phenyl isocyanate), trimellitic anhydride and benzoic acid by ¹H and ¹³C NMR spectroscopy and size-exclusion chromatography allows the determination of their absolute number-average molecular weights M?_{n, abs}. Viscosimetric measurements reveal that, dissolved in N-methyl-2-pyrrolidone, these low molecular weight PIAs should be semi-rigid because of the presence of very short crystalline chains. By using the semi-empirical Fox-Flory relation, the extrapolated glass transition temperature equals 300°C for high molecular weight.     

Impact of a patient education program on adherence to HIV medication: a randomized clinical trial

Patients' knowledge of their HIV condition and its treatment, which has been recognized as a factor that influences adherence to antiretroviral therapy, can be improved through educational programs. This prospective, randomized, controlled trial compared an experimental group that participated in an educational program and a control group with standard care. The study evaluated the impact of an educational intervention on adherence to antiretroviral therapy, patients' knowledge, quality of life, and therapeutic response in patients treated with highly active antiretroviral therapy. Three hundred twenty-six patients were analyzed at inclusion. A higher level of adherence was associated with patients who were older, had higher incomes, and did not smoke. CD4 cell count and plasma viral load were correlated with adherence at entry. The educational intervention had an impact on adherence and knowledge in the experimental group at 6 months, which was maintained at 12 and 18 months. A delayed increase in adherence was observed in the control group at 12 months. No significant impact on quality of life was observed over time. The patients' health status improved in 56% of the experimental group subjects and 50% of the control subjects. However, no significant impact was shown on CD4 cell count and plasma viral load. This study shows that an educational intervention improves adherence to antiretroviral regimens and health status and suggests that it should be initiated early in therapy.