Expression, purification and identification of Pla a1 in a codon-optimized Platanus pollen allergen

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 PM_2.5 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 PM_2.5 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 PM_2.5 could aggravate autophagy, which in turn effectively suppressed ROS and TSLP levels, leading to the alleviation of the immune response and pulmonary inflammation.

Allergenicity of recombinant Humulus japonicus pollen allergen 1 after combined exposure to ozone and nitrogen dioxide

Ozone (O₃) and nitrogen dioxide (NO₂) are thought to play primary roles in aggravating air pollution-induced health problems. However, the effects of joint O₃/NO₂ on the allergenicity of pollen allergens are unclear. Humulus japonicus pollen allergen 1 (Hum j1) is a profilin protein that causes widespread pollinosis in eastern Asia. In order to study the effects of combined O₃/NO₂ on the allergenicity of Hum j1, tandem six-histidine peptide tag (His6)-fused recombinant Hum j1 (rHum j1) was expressed in a prokaryotic system and purified through His6 affinity chromatography. The purified rHum j1 was used to immunize SD rats. Rat sera with high titers of IgG and IgE antibodies against rHum j1 were used for allergenicity quantification. The rHum j1 was exposed to O₃/NO₂, and changes in allergenicity of the exposed rHum j1 were assayed using the immunized rat antibodies. Tandem LC-MS/LC (liquid chromatography-mass spectrometer/liquid chromatography spectrometer) chromatography and UV and circular dichroism (CD) spectroscopy were used to study the structural changes in rHum j1. Our data demonstrated that a novel disulfide bond between the sulfhydryl groups of two neighboring cysteine molecules was formed after the rHum j1 exposure to joint O₃/NO₂, and therefore IgE-binding affinity was increased and the allergenicity was reinforced. Our results provided clues to elucidate the mechanism behind air pollution-induced increase in pollinosis prevalence.

Expression, purification and epitope analysis of Pla a 2 allergen from Platanus acerifolia pollen

Platanus acerifolia is one of the major sources of outdoor allergens to humans, and can induce allergic asthma, rhinitis, dermatitis and other allergic diseases. Pla a 2 is a polygalacturonase and represents the major allergen identified in P. acerifolia pollen. The aim of the present study was to express and purify Pla a 2, and to predict B and T cell epitopes of Pla a 2. The gene encoding Pla a 2 was cloned into the pET28a vector and subsequently transfected into ArcticExpress™ (DE3) Escherichia coli cells; purified Pla a 2 was analyzed by western blot analysis. The results of the present study revealed that the Pla a 2 allergen has the ability to bind immunoglobulin E within the sera of patients allergic to P. acerifolia pollen. In addition, the B cell epitopes of Pla a 2 were predicted using the DNAStar Protean system, Bioinformatics Predicted Antigenic Peptides and BepiPred 1.0 software; T cell epitopes were predicted using NetMHCIIpan ‑3.0 and ‑2.2. In total, eight B cell epitopes (15‑24, 60‑66, 78‑86, 109‑124, 232‑240, 260‑269, 298‑306 and 315‑322) and five T cell epitopes (62‑67, 86‑91, 125‑132, 217‑222 and 343‑350) were predicted in the present study. These findings may be used to improve allergen immunotherapies and reduce the frequency of pollen‑associated allergic reactions.

Expression and purification of a major allergen, Pla a 1, from Platanus acerifolia pollen and the preparation of its monoclonal antibody

Platanus acerifolia pollen is considered an important source of airborne allergens in numerous cities. Pla a 1 is a major allergen from P. acerifolia pollen. The present study aimed to express and purify Pla a 1, and to prepare its monoclonal antibody. In the present study, the Pla a 1 gene was subcloned into a pET‑28a vector and transformed into the ArcticExpress™ (DE3) RP Escherichia coli host strain. The purified Pla a 1 was then used to immunize BALB/c mice. When serum detection was positive, spleen cells were isolated from the mice and fused with SP2/0 myeloma cells at a ratio of 10:1. Hybridoma cells were screened by indirect ELISA and limiting dilution. Positive cells were used to induce the formation of antibody‑containing ascites fluid, and the antibodies were purified using protein A‑agarose. The results of the present study demonstrated that recombinant Pla a 1 was successfully expressed and purified, and exhibited positive immunoglobulin E‑binding to serum from patients allergic to P. acerifolia. A total of 11 hybridomas that steadily secreted anti‑Pla a 1 antibody were obtained and an immunoblotting analysis indicated that all of these monoclonal antibodies specifically recognized the Pla a 1 protein. These results suggested that specific anti‑Pla a 1 antibodies may be obtained, which can be used for the rapid detection of Pla a 1 allergens and in the preparation of vaccines against P. acerifolia pollen.