Air quality in the California San Joaquin Valley is among the worst in the nation, causing allergies and potentially long-term medical conditions. The air in the San Joaquin Valley is unique due to the presence of high levels of agricultural dust.  It is well documented that the vast majority of allergens are proteins. While proteins are nonvolatile, they can travel through the air on aerosol particles. This project is focused on the proteomic analysis of inhalable aerosols from the San Joaquin Valley.  It is anticipated that this study will shed light on human exposure to protein allergens via agricultural dust inhalation.<br/><br/>To date, our efforts have successfully optimized conditions for sampling inhalable dust from the San Joaquin Valley. It is critical that sampling simulates inhalable conditions to the extent possible. To accomplish this, a “button aerosol sampler” was employed for sampling. This type of aerosol sampler uses borosilicate glass filters with a one-micron “nominal” pore size. To simulate respiratory conditions, the sampler was connected to a pump that pulled at rate of 4 L/min.  The aerosol sampler was placed at a location outside the California State University Stanislaus campus.  Sampling intervals of one week were found to be optimal for sufficient sample acquisition for protein analysis. <br/>Collected inhalable dust samples were subsequently analyzed to determine their protein mass percent. Proteins were solubilized from dust samples via sonication for one hour in 700 mL of an aqueous buffer solution (25 mM Tris, 192 mM glycine and 0.1 % SDS).  The samples were then centrifuged at 14,800 x g for 15 minutes.  Protein concentrations in the supernatant were determined by a Lowry protein assay with bovine serum albumin as an external standard.  The protein mass % from inhalable dust was found to be ~7% by mass.  This amount of protein is sufficient for SDS-PAGE analysis with Coomassie stain, which is compatible with mass spectrometry.  The current focus of this project is to carry out SDS-PAGE on the acquired protein samples.  The gel bands will then be excised and digested with trypsin.  The resulting peptides will be analyzed by electrospray tandem mass spectrometry, which will be used to identify the proteins present in the inhalable dust samples.  Knowledge of the specific proteins that are contained within the inhalable dust in the San Joaquin Valley could open the possibility for more targeted treatment options.

Proteomic characterization of inhalable dust from the California San Joaquin Valley

253rd National Meeting (2017)

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