Novel Mouse Models of Fungal Asthma.

Alternaria alternata is a ubiquitous fungus and a major allergen associated with the development of asthma. Inhalation of intact spores is the primary cause of human exposure to fungal allergen. However, allergen-rich cultured fungal filtrates are oftentimes used in the current models of fungal sensitization that do not fully reflect real-life exposures. Thus, establishing novel spore exposure models is imperative. In this study, we established novel fungal exposure models of both adult and neonate to live spores. We examined pathophysiological changes in the spore models as compared to the non-exposure controls and also to the conventional filtrate models. While both Alternaria filtrate- and spore-exposed adult BALB/c mice developed elevated airway hyperresponsiveness (AHR), filtrates induced a greater IgE mediated response and higher broncholavage eosinophils than spores. In contrast, the mice exposed to Alternaria spores had higher numbers of neutrophils. Both exposures induced comparable levels of lung tissue inflammation and mucous cell metaplasia (MCM). In the neonatal model, exposure to Alternaria spores resulted in a significant increase of AHR in both adult and neonatal mice. Increased levels of IgE in both neonatal and adult mice exposed to spores was associated with increased eosinophilia in the treatment groups. Adult demonstrated increased numbers of lymphocytes that was paralleled by increased IgG1 production. Both adults and neonates demonstrated similarly increased eosinophilia, IgE, tissue inflammation and MCM.

Alternaria induces airway epithelial cytokine expression independent of protease-activated receptor.

BACKGROUND AND OBJECTIVE: A novel fungal allergen, Alternaria (Alt), has been previously shown to associate with the pathogenesis of allergic rhinitis and bronchial asthma, particularly in arid and semi-arid regions. Airway epithelial cells are among the first to encounter Alt, and epithelial cytokine production and subsequent airway inflammation are early events in the response to Alt exposure. However, the underlying mechanism is unclear. As protease-activated receptor 2 (PAR2) has been implicated in most of the Alt-induced biological events, we investigated the regulation of airway inflammation and epithelial cytokine expression by PAR2. METHODS: Wild-type (WT) and Par2 knockout (Par2-KO) mice were used to evaluate the in vivo role of PAR2. Primary human and mouse airway epithelial cells were used to examine the mechanistic basis of epithelial cytokine regulation in vitro. RESULTS: Surprisingly, Par2 deficiency had no negative impact on the change of lung function, inflammation and cytokine production in the mouse model of Alt-induced asthma. Alt-induced cytokine production in murine airway epithelial cells from Par2-KO mice was not significantly different from the WT cells. Consistently, PAR2 knockdown in human cells also had no effect on cytokine expression. In contrast, the cytokine expressions induced by synthetic PAR2 agonist or other asthma-related allergens (e.g. cockroach extracts) were indeed mediated via a PAR2-dependent mechanism. Finally, we found that EGFR pathway was responsible for Alt-induced epithelial cytokine expression. CONCLUSION: The activation of EGFR, but not PAR2, was likely to drive the airway inflammation and epithelial cytokine production induced by Alt.

Suppression of relaxin receptor RXFP1 decreases prostate cancer growth and metastasis.

Relaxin (RLN) is a small peptide hormone expressed in several cancers of reproductive and endocrine organs. Increased expression of RLN in prostate cancer correlates with aggressive cancer. RLN G-protein-coupled receptor (RLN family peptide receptor 1, RXFP1) is expressed in both androgen receptor (AR)-positive and -negative prostate cancers as well as in prostate cancer cell lines. RLN behaves as a cell growth factor and increases invasiveness and proliferation of cancer cells in vitro and in vivo. The objective of this study is to determine whether downregulation of RXFP1 expression using small interfering RNA (siRNA) reduces cancer growth and metastasis in a xenograft model of prostate cancer. We used two well-characterized prostate adenocarcinoma cell lines, AR-positive LNCaP cells and AR-negative PC3 cells. The tumors were established in nude male mice by s.c. injections. Intratumoral injections of siRNAs loaded on biodegradable chitosan nanoparticles led to a downregulation of RXFP1 receptor expression and a dramatic reduction in tumor growth. In LNCaP tumors, the siRNA treatment led to an extensive necrosis. In PC3 xenografts treated with siRNA against RXFP1, the smaller tumor size was associated with the decreased cell proliferation and increased apoptosis. The downregulation of RXFP1 resulted in significant decrease in metastasis rate in PC3 tumors. Global transcriptional profiling of PC3 cells treated with RXFP1 siRNA revealed genes with significantly altered expression profiles previously shown to promote tumorigenesis, including the downregulation of MCAM, MUC1, ANGPTL4, GPI, and TSPAN8. Thus, the suppression of RLN/RXFP1 may have potential therapeutic benefits in prostate cancer.

Extraction and labeling methods for microarrays using small amounts of plant tissue.

Procedures were developed to maximize the yield of high-quality RNA from small amounts of plant biomass for microarrays. Two disruption techniques (bead milling and pestle and mortar) were compared for the yield and the quality of RNA extracted from 1-week-old Arabidopsis thaliana seedlings (approximately 0.5-30 mg total biomass). The pestle and mortar method of extraction showed enhanced RNA quality at the smaller biomass samples compared with the bead milling technique, although the quality in the bead milling could be improved with additional cooling steps. The RNA extracted from the pestle and mortar technique was further tested to determine if the small quantity of RNA (500 ng-7 microg) was appropriate for microarray analyses. A new method of low-quantity RNA labeling for microarrays (NuGEN Technologies, Inc.) was used on five 7-day-old seedlings (approximately 2.5 mg fresh weight total) of Arabidopsis that were grown in the dark and exposed to 1 h of red light or continued dark. Microarray analyses were performed on a small plant sample (five seedlings; approximately 2.5 mg) using these methods and compared with extractions performed with larger biomass samples (approximately 500 roots). Many well-known light-regulated genes between the small plant samples and the larger biomass samples overlapped in expression changes, and the relative expression levels of selected genes were confirmed with quantitative real-time polymerase chain reaction, suggesting that these methods can be used for plant experiments where the biomass is extremely limited (i.e. spaceflight studies).