IgE-mediated anaphylaxis caused by bites of the pigeon tick Argas reflexus: cloning and expression of the major allergen Arg r 1

BACKGROUND: Anaphylactic reactions caused by bites of the European pigeon tick Argas reflexus are repeatedly reported. This soft-backed tick is a parasite of wild pigeons colonizing urban buildings and houses. Occasionally the ticks can bite human beings, inducing anaphylactic reactions in sensitized patients. OBJECTIVE: Our aim was to characterize the major allergen implicated in a series of anaphylactic reactions caused by Argas bites and to produce the allergen as recombinant protein for diagnostic purposes. METHODS: Protein extracts were prepared from whole A reflexus bodies, and IgE immunoblots were performed with sera from 13 patients who had an anaphylactic reaction with pigeon tick bites. A cDNA expression library was constructed from whole ticks and screened with a polyclonal rabbit antiserum raised against the major allergen. RESULTS: The cDNA coding for the dominant allergen Arg r 1 could be isolated. It encodes a protein belonging to the lipocalin family. Allergenicity of the recombinant Arg r 1 was confirmed by immunoblot, ELISA, and intradermal skin tests. CONCLUSION: The dominant allergen of A reflexus has been isolated and the corresponding cDNA cloned. The recombinant protein, a lipocalin, was expressed in Escherichia coli and was shown to be immunoreactive in vitro and in vivo. Recombinant Arg r 1 was used as a diagnostic tool in a series of anaphylactic reactions caused by pigeon tick bites.     

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.     

Prenatal diagnosis of trisomy 1q21-qter: case report and review of literature

We report on a midtrimester fetus with multiple malformations, who was prenatally found to have pure partial trisomy 1q with duplication 1q21-qter. Prenatal ultrasound at 23 gestational weeks demonstrated craniofacial dysmorphism, ventriculomegaly, hand anomalies, and multiple visceral anomalies including cardiac defect, duodenal atresia, omphalocele, and urethral obstruction in the fetus. After pregnancy termination, external morphologic examination confirmed the sonographic characteristics, but autopsy was refused. Cytogenetic analysis (GTG banding) and subtelomeric probes (FISH) demonstrated an aberrant karyotype 46,XY,der(1)(1qter --> 1q21::1p36.3 --> 1qter) in a total of 139 amniotic fluid cells. Trisomy of the long arm of chromosome 1 is a rare condition. Large duplications of almost the entire 1q had so far been described in five mosaic cases. The present case and review of the literature suggest that duplication 1q21-qter is a serious condition with pre- or perinatal demise of all reported cases. This case further delineates the phenotype in trisomy 1q.     

Expression of Anaplasma marginale major surface protein 2 operon-associated proteins during mammalian and arthropod infection

The antigenically variant major surface protein 2 (MSP2) of Anaplasma marginale is expressed from a 3.5-kb operon that contains, in a 5'-to-3' direction, four open reading frames, opag3, opag2, opag1, and msp2. This operon structure was shown to be conserved among genotypically and phenotypically distinct A. marginale, A. ovis, and A. centrale strains. The individual OpAG amino acid sequences are highly conserved among A. marginale strains, with identities ranging from 95 to 99%. OpAG2 and OpAG3 were expressed by all examined A. marginale strains during the acute rickettsemia in the mammalian host and, like MSP2, localize to the bacterial surface. OpAG2 and OpAG3 were also expressed in an infected Ixodes scapularis tick cell line. In contrast, the same A. marginale strains expressed only OpAG2 in two different Dermacentor spp. during transmission feeding. OpAG1 expression was not detected in the infected mammalian host, the infected tick cell line, or within infected Dermacentor ticks. The differential expression of outer membrane proteins from within an operon is a novel finding in tick-transmitted bacteria, and the regulation of expression may be broadly applicable to understanding how the pathogen adapts to the mammalian host-tick vector transition.     

Up-regulation of endothelial nitric oxide synthase inhibits pulmonary leukocyte migration following lung ischemia-reperfusion in mice

Endogenous nitric oxide (NO) is known to modulate post-ischemic inflammatory response in various organs. However, the role of nitric oxide synthase isoforms (NOS) in mediating pulmonary post-ischemic inflammatory response is poorly understood. We therefore studied post-ischemic endothelial adhesion molecule expression and leukocyte migration in endothelial NOS knockout (eNOS-KO) mice subjected to pulmonary ischemia and reperfusion in vivo. Under anesthesia and mechanical ventilation, the left pulmonary hilum in wild-type (WT) and eNOS-KO mice was clamped for 1 hour, followed by reperfusion for up to 24 hours. In WT mice, we observed a selective up-regulation of both eNOS mRNA and protein in lung tissue, while inducible NOS (iNOS) and neuronal NOS (nNOS) remained unchanged. Survival in eNOS-KO mice was reduced due to severe pulmonary edema, underlining an increased susceptibility to ischemia-reperfusion (I/R) injury. Interstitial tissue infiltration by CD18- and CD11a-positive white blood cells as well as lung tissue water content peaked at 5 hours of reperfusion and were found significantly higher than in WT mice. Enhanced leukocyte-endothelial interaction was associated with pronounced up-regulation of vascular cell adhesion molecule (VCAM) in eNOS-KO mice during post-ischemic reperfusion. We conclude that eNOS attenuates post-ischemic inflammatory injury to the lung most probably via inhibition of endothelial adhesion molecule expression.     

The effect of erroneous responses on response monitoring in patients with major depressive disorder: a study with event-related potentials

Perceived failure is reported to have detrimental effects on subsequent performance in patients with major depressive disorder. We investigated the error-related negativity (ERN)/error negativity (Ne), an electrophysiological correlate of response monitoring, using a 64-channel EEG. Sixteen patients with DSM-IV major depressive disorder and 16 matched controls participated in an Eriksen flanker task with continuous performance feedback that signaled monetary reward. Compared to controls, patients with major depressive disorder showed a less negative ERN/Ne in error trials following error trials. This result might reflect impaired response monitoring processes in major depressive disorder resulting from an underactivity in a central reward pathway and/or a deficit in strategic reasoning.     

Maturation of Peyer's patch dendritic cells in vitro upon stimulation via cytokines or CD40 triggering

In mouse Peyer's patches (PP), dendritic cells (DC) are localized in T cell areas as NLDC145⁺ CD11c+ cells, and in the dome and corona region of the follicle as NLDC145? CD11c+ cells, respectively, suggesting the presence of two different DC populations with distinct roles in antigen uptake, processing, and presentation. However, it is not clear how this relates to DC maturation. In this report, we demonstrate that freshly-isolated CD11c+ DC have the properties of immature DC since they endocytose soluble antigens, phagocytose particulate material such as latex beads, synthetize major histocompatibility complex (MHC) class II and invariant chain, but, at the same time, display low stimulatory activity for resting T cells, as shown in mixed-lymphocyte reaction and oxidative mitogenesis assays. When cultured for 24 h in the presence of the cytokines granulocyte-macrophage colony-stimulating factor and tumor necrosis factor or anti-CD40, the cells undergo dramatic phenotypic and functional changes characteristic of DC maturation. After 24 h stimulation in vitro, CD11c+ cells lose the ability to take up proteins such as ovalbumin, and in parallel with this decline, the biosynthesis of MHC class II and invariant chain is dramatically down-regulated or eliminated. On the other hand cells treated in vitro exhibit on the cell surface higher levels of MHC class II, of co-stimulatory molecules (CD80, CD86), of adhesion molecules (CD44, intercellular adhesion molecule-1), and acquire expression of the interdigitating DC surface marker NLDC145. Concomitantly, the ability to stimulate naive T cells drastically increased after in vitro treatment with both stimuli. Taken together, our results indicate that the majority of DC in the PP are immature in terms of their antigen-uptake capacity. These sentinel antigen presenting cells are strategically positioned at the dome region of PP, where antigens are transcytosed via the M cells from the gut lumen. A second population of mature interdigitating NLDC145⁺ CD11c+ DC stimulates naive unprimed T cells in interfollicular areas by up-regulation of surface ligands and accessory signals.