Steroids Inhibit Eosinophil Accumulation and Downregulate Hematopoietic Chemotaxic Prostaglandin D2 Receptor in Aspirin-Exacerbated Respiratory Disease.

BACKGROUND: Aspirin-exacerbated respiratory disease (AERD) is characterized by eosinophilic rhinosinusitis, nasal polyposis, aspirin sensitivity, and asthma. Aims/Objectives: This study aims to identify a mechanism to target for the future treatment of AERD via the elucidation of the effect of systemic steroids on the expression of hematopoietic prostaglandin D2 synthase (HPGDS) and chemotaxic prostaglandin D2 (DP2) receptor relative to eosinophil activation in the nasal polyps of patients with AERD. MATERIALS AND METHODS: Among 37 patients undergoing endoscopic sinus surgery, 28 received systemic steroids preoperatively. Nasal polyps were harvested from all 37 patients. After routine processing of paraffin sections, immunohistochemistry was performed using specific antibodies for HPGDS, eosinophil peroxidase (EPX), and DP2. RESULTS: Expression of HPGDS, DP2, and EPX by eosinophils was higher and more frequent in patients with non-preoperative steroid therapy. Likewise, HPGDS and DP2 were highly expressed in activated eosinophils in the nasal polyps, but not in normal eosinophils. CONCLUSION AND SIGNIFICANCE: This study provides clear evidence that systemic steroid therapy inhibits eosinophil activation and decreases HPGDS and DP2 expression in patients with AERD, indicating a reduction in prostaglandin D2 production and hence control hyperplasia of nasal polyps.

Nonredundant roles of Sema4A in the immune system: defective T cell priming and Th1/Th2 regulation in Sema4A-deficient mice.

The class IV semaphorin Sema4A provides a costimulatory signal to T cells. To investigate the possible developmental and regulatory roles of Sema4A in vivo, we generated Sema4A-deficient mice. Although Sema4A-deficient mice develop normally, DCs and T cells from knockout mice display poor allostimulatory activities and T helper cell (Th) differentiation, respectively. Interestingly, in addition to its expression on DCs, Sema4A is upregulated on Th1-differentiating cells, and it is necessary for in vitro Th1 differentiation and T-bet expression. Consequently, in vivo antigen-specific T cell priming and antibody responses against T cell-dependent antigens are impaired in the mutant mice. Additionally, Sema4A-deficient mice exhibit defective Th1 responses. Furthermore, reconstitution studies with antigen-pulsed DCs reveal that DC-derived Sema4A is important for T cell priming, while T cell-derived Sema4A is involved in developing Th1 responses. Collectively, these results indicate a nonredundant role of Sema4A not only in T cell priming, but also in the regulation of Th1/Th2 responses.

An observation of the initial stage towards a symbiotic relationship.

Two well-characterized and phylogeneticaly different species, Escherichia coli and Dictyostelium discoideum, were used as the model organisms. When the two species were mixed and allowed to grow on minimal agar plates at 22 degrees C, remarkably, the two species achieved a state of coexistence at an average of 2-4 weeks. In addition, the emerged colonies housing the coexisting species had a mucoidal nature that was not observed from its origin. Moreover, the state of coexistence was confirmed to be stable, and so was the mucoidal nature of the emerged colonies. Comparing with the pure E. coli origin, the mucoidal colony showed a significant increase in higher molecular weight extracellular components, with polysaccharides as the major constituent. Qualitative analysis of the monosaccharide contents in the extracellular components of the mucoidal colony revealed not only a significant increase in the glucose content, but also significant amount of additional xylose and galactose. The system permits the initial stages of the development of relationship between two species be captured within a short period of time. This feature, together with being simple and reproducible in laboratory conditions, provides a new model system for the study of symbiosis, especially when initial stages are concerned.

Importance of compartment formation for a self-encoding system.

A self-encoding system designed to have strict "compartition" of the molecules, i.e., to contain only a single molecule of DNA in each compartment, was established, and its evolutionary fate was analyzed. The system comprised the Thermus thermophilus DNA polymerase gene as the informational molecule and its protein product replicating the gene as the functional molecule. Imposing strict compartition allows the self-encoding system to last up to at least the tenth generation, whereas the system ceased to work after the third generation when loose compartition initiated with 100 molecules was imposed. These results provide experimental evidence on the importance of compartition for the maintenance of a self-encoding system. In addition, the extent of diversity in self-replication activity of the compartments was found to be another vital difference in the evolutionary dynamics between the strict and loose compartitions. Although the system with strict compartition provides widely diversified activity of the compartments at each generation, the values of the activity diverge only within a small range in the system with loose compartition. When the variety in the activity of a compartment is small, functional selection becomes weak, and to conform Darwinian evolution may become unfeasible. Therefore, strict compartition is essential for the evolvability of a self-encoding system.