Subpollens delivery of Platanus acerifolia pollen allergen Pla a3 and nucleic acid into lungs and cells.

Pollen allergy is a very serious seasonal respiratory disease. However, there has been a lack of understanding how pollen allergens enter the body and act on cells. This study focused on the release, transport and characteristic of Pla a3 allergen of the Platanus acerifolia pollen. Pla a3 protein was purified by prokaryotic expression system for preparation of polyclonal antibody. The distribution and release of Pla a3 protein in pollen were observed by immunohistochemistry. Mice were immunized with purified Pla a3 protein and SPPs, respectively. The pathological examination of mouse lung tissue proved that SPPs, as a fine particle in the range of 0.1-1µm, can enter the deep part of the lung directly through the respiratory tract and led to inflammation. Furthermore, DAPI staining confirmed a certain amount of nucleic acids in SPPs. After incubation with SPPs for 6 h, the Pla a3 mRNA could be detected in A549 cells by PCR. This suggests that nucleic acid wrapped in SPPs could be delivered into A549 cells. These results could provide a new clue and experimental data accumulation for further study on the mechanism of pollen sensitization.

One novel cis-element is essential for correct DYSFUNCTIONAL TAPETUM 1 (DYT1) expression in Arabidopsis thaliana.

KEY MESSAGE: We studied the function of DYT1 promoter, found the important sectors controlling specific expression of DYT1 , and identified a new cis -element for further investigation of DYT1 upstream genes. DYT1 is a core regulatory gene for tapetum development in Arabidopsis thaliana. However, the mechanism leading to DYT1 tapetum-preferential expression is still unknown up to date. Here we employed promoter truncation and deletion assay to identify a 'CTCC' cis-element, which was essential for correct DYT1 expression within DYT1 promoter region. Through comparing truncated DYT1 promoter-driven GFP expression, the -481 to -513 bp region from the start point of transcription (SPT) of DYT1 was found indispensable for proper DYT1 expression. Further deletion assay around this region revealed that an approximate -468 bp 'CTCC' sequence deletion abolished normal DYT1 expression completely. Bioinformatics assay suggested that this 'CTCC' motif was potentially a novel DNA-recognition sequence, providing new clue for investigating relationship between DYT1 and its upstream genes.

Ambient particulate matter-associated autophagy alleviates pulmonary inflammation induced by Platanus pollen protein 3 (Pla3).

Subpollen particles (SPPs) with diameter less than 1 mm released from allergenic pollen grains contain allergens could trigger asthma and lung inflammation after being inhaled. In the meaning time, ambient fine particles attached on the pollen grains could have further effects on the inflammation. However, the mechanisms underlying these phenomena have not been fully elucidated. In this study, the effects of autophagy triggered by PM2.5 and Platanus SPPs were evaluated by using the A549 cell lines and a pollen sensitized rat model. First, autophagy in A549 cells was analyzed after exposure to PM2.5 using acridine orange staining, real-time quantitative PCR (qRT-PCR), and western blot (WB) assays. The increased levels of ROS, superoxide dismutase, and malonaldehyde in the lung homogenates of rats exposed to SPPs indicated that inflammatory response was triggered in the lungs. Treatment with autophagy-inhibiting drugs showed that autophagy suppressed ROS formation and decreased the production of thymic stromal lymphopoietin (TSLP), a critical pathway altering the inflammatory response. Although the effect was indirect, autophagy appeared to negatively regulate TSLP levels, resulting in a compromised immune response. These results suggested that SPPs promote ROS generation and increase TSLP levels, triggering downstream inflammation reactions. However, ambient PM2.5 could aggravate autophagy, which in turn effectively suppressed ROS and TSLP levels, leading to the alleviation of the immune response and pulmonary inflammation.