Respiratory allergy to Blomia tropicalis: Immune response in four syngeneic mouse strains and assessment of a low allergen-dose,short-term experimental model

Background

The dust mite Blomia tropicalis is an important source of aeroallergens in tropical areas. Although a mouse model for B. tropicalis extract (BtE)-induced asthma has been described, no study comparing different mouse strains in this asthma model has been reported. The relevance and reproducibility of experimental animal models of allergy depends on the genetic background of the animal, the molecular composition of the allergen and the experimental protocol.

Objectives

This work had two objectives. The first was to study the anti-B. tropicalis allergic responses in different mouse strains using a short-term model of respiratory allergy to BtE. This study included the comparison of the allergic responses elicited by BtE with those elicited by ovalbumin in mice of the strain that responded better to BtE sensitization. The second objective was to investigate whether the best responder mouse strain could be used in an experimental model of allergy employing relatively low BtE doses.

Methods

Groups of mice of four different syngeneic strains were sensitized subcutaneously with 100 μg of BtE on days 0 and 7 and challenged four times intranasally, at days 8, 10, 12, and 14, with 10 μg of BtE. A/J mice, that were the best responders to BtE sensitization, were used to compare the B. tropicalis-specific asthma experimental model with the conventional experimental model of ovalbumin (OVA)-specific asthma. A/J mice were also sensitized with a lower dose of BtE.

Results

Mice of all strains had lung inflammatory-cell infiltration and increased levels of anti-BtE IgE antibodies, but these responses were significantly more intense in A/J mice than in CBA/J, BALB/c or C57BL/6J mice. Immunization of A/J mice with BtE induced a more intense airway eosinophil influx, higher levels of total IgE, similar airway hyperreactivity to methacholine but less intense mucous production, and lower levels of specific IgE, IgG1 and IgG2 antibodies than sensitization with OVA. Finally, immunization with a relatively low BtE dose (10 μg per subcutaneous injection per mouse) was able to sensitize A/J mice, which were the best responders to high-dose BtE immunization, for the development of allergy-associated immune and lung inflammatory responses.

Conclusions

The described short-term model of BtE-induced allergic lung disease is reproducible in different syngeneic mouse strains, and mice of the A/J strain was the most responsive to it. In addition, it was shown that OVA and BtE induce quantitatively different immune responses in A/J mice and that the experimental model can be set up with low amounts of BtE.     

Rats go genomic

A report on the meeting 'Rat Genomics and Models', Cold Spring Harbor, USA, 8-11 December 2005.     

Type IV P-type ATPases Distinguish Mono- versus Diacyl Phosphatidylserine Using a Cytofacial Exit Gate in the Membrane Domain

Type IV P-type ATPases (P4-ATPases) use the energy from ATP to “flip” phospholipid across a lipid bilayer, facilitating membrane trafficking events and maintaining the characteristic plasma membrane phospholipid asymmetry. Preferred translocation substrates for the budding yeast P4-ATPases Dnf1 and Dnf2 include lysophosphatidylcholine, lysophosphatidylethanolamine, derivatives of phosphatidylcholine and phosphatidylethanolamine containing a 7-nitro-2-1,3-benzoxadiazol-4-yl (NBD) group on the sn-2 C6 position, and were presumed to include phosphatidylcholine and phosphatidylethanolamine species with two intact acyl chains. We previously identified several mutations in Dnf1 transmembrane (TM) segments 1 through 4 that greatly enhance recognition and transport of NBD phosphatidylserine (NBD-PS). Here we show that most of these Dnf1 mutants cannot flip diacylated PS to the cytosolic leaflet to establish PS asymmetry. However, mutation of a highly conserved asparagine (Asn-550) in TM3 allowed Dnf1 to restore plasma membrane PS asymmetry in a strain deficient for the P4-ATPase Drs2, the primary PS flippase. Moreover, Dnf1 N550 mutants could replace the Drs2 requirement for growth at low temperature. A screen for additional Dnf1 mutants capable of replacing Drs2 function identified substitutions of TM1 and 2 residues, within a region called the exit gate, that permit recognition of dually acylated PS. These TM1, 2, and 3 residues coordinate with the “proline + 4” residue within TM4 to determine substrate preference at the exit gate. Moreover, residues from Atp8a1, a mammalian ortholog of Drs2, in these positions allow PS recognition by Dnf1. These studies indicate that Dnf1 poorly recognizes diacylated phospholipid and define key substitutions enabling recognition of endogenous PS.     

A Dutch guideline for the treatment of scoliosis in neuromuscular disorders

Background

Children with neuromuscular disorders with a progressive muscle weakness such as Duchenne Muscular Dystrophy and Spinal Muscular Atrophy frequently develop a progressive scoliosis. A severe scoliosis compromises respiratory function and makes sitting more difficult. Spinal surgery is considered the primary treatment option for correcting severe scoliosis in neuromuscular disorders. Surgery in this population requires a multidisciplinary approach, careful planning, dedicated surgical procedures, and specialized after care.

Methods

The guideline is based on scientific evidence and expert opinions. A multidisciplinary working group representing experts from all relevant specialties performed the research. A literature search was conducted to collect scientific evidence in answer to specific questions posed by the working group. Literature was classified according to the level of evidence.

Results

For most aspects of the treatment scientific evidence is scarce and only low level cohort studies were found. Nevertheless, a high degree of consensus was reached about the management of patients with scoliosis in neuromuscular disorders. This was translated into a set of recommendations, which are now officially accepted as a general guideline in the Netherlands.

Conclusion

In order to optimize the treatment for scoliosis in neuromuscular disorders a Dutch guideline has been composed. This evidence-based, multidisciplinary guideline addresses conservative treatment, the preoperative, perioperative, and postoperative care of scoliosis in neuromuscular disorders.     

Evolution of the cutaneous immune response to experimental Haemophilus ducreyi infection and its relevance to HIV-1 acquisition

Haemophilus ducreyi causes the sexually transmitted disease chancroid, which facilitates HIV-1 transmission. Skin biopsies were obtained from subjects experimentally infected with H. ducreyi to study the evolution of the immune response and immunophenotypes relevant to transmission of HIV-1. Compared with peripheral blood, there was an enrichment of T cells and macrophages after 48 h of infection in the skin. Neutrophils became the predominant cell type by 7-9 days. By immunohistochemistry, macrophage-inflammatory protein-1alpha was not present early in infection, but was abundant at later stages. RANTES was present throughout the papular and pustular stages of experimental infection, but not present in uninfected control skin. Stromal cell-derived factor-1 was present at low levels in all samples examined. Macrophages in lesions had significantly increased expression of CCR5 and CXCR4 compared with peripheral blood cells, and CD4 T cells had significant up-regulation of CCR5. The magnitude of increased expression of these receptors was not replicated when PBMCs were incubated with H. ducreyi or H. ducreyi lipooligosaccharide in vitro. Together with the disruption of mucosal and skin barriers, the presence of cells with up-regulated HIV-1 coreceptors in H. ducreyi-infected lesions may provide an environment that facilitates the acquisition of R5 (CCR5), X4 (CXCR4), and dual-tropic HIV-1 strains.     

Taurine blocks spontaneous cone contraction but not horizontal cell dark suppression in isolated goldfish retina

The objective of this study was to investigate the effects of taurine on cone retinomotor movements and the responses of cone-driven horizontal cells in dark-adapted teleost retina. In isolated goldfish retina preparations maintained in the dark, cones spontaneously contracted, and the responses of horizontal cells were suppressed. Addition of 5 mM taurine to the physiological solution blocked the spontaneous contraction of cones in the dark but did not block the dark-suppression of horizontal cell responses. These results indicate that the mechanism that leads to horizontal cell dark suppression is not sensitive to taurine. Although both cone retinomotor position and horizontal cell responsiveness are known to be modulated by dopamine, the present results do not support the hypothesis that taurine inhibits dopamine release in the dark because only spontaneous cone contraction was affected by taurine. These results also indicate that spontaneous cone contraction in the dark is not the cause of horizontal cell dark suppression because, in the presence of taurine, cones were elongated yet horizontal cell responses were still suppressed. Consequently, these results make it clear that horizontal cell dark suppression is not an artifact produced by incubating isolated teleost retina preparations in taurine-free physiological solution.     

产β—葡萄糖苷酶真菌诱变菌株快速筛选方法

报道了一种快速筛选产β-葡萄糖管酶真菌诱变菌株的方法。该法利用ρNPG经β-葡萄糖苷酶水解,水解产物ρNP在碱性条件下显色的原理。采用自制的特殊初筛平皿.经一年多的实践应用表明此法具有简便、灵敏、筛子消耗量小、筛选效率高等优点。