Aerosolized aqueous dust extracts collected near a drying lake trigger acute neutrophilic pulmonary inflammation reminiscent of microbial innate immune ligands

Background: A high incidence of asthma is prevalent among residents near the Salton Sea, a large inland terminal lake in southern California. This arid region has high levels of ambient particulate matter (PM); yet while high PM levels are often associated with asthma in many environments, it is possible that the rapidly retreating lake, and exposed playa or lakebed, may contribute components with a specific role in promoting asthma symptoms.Objectives: Our hypothesis is that asthma may be higher in residents closest to the Salton Sea due to chronic exposures to playa dust. Playa emissions maybe concentrating dissolved material from the lake, with microbial components capable of inducing pulmonary innate immune responses. To test this hypothesis, we used a mouse model of aerosol exposures to as-sess the effects of playa dust.Methods: From dust collected around the Salton Sea region, aqueous extracts were used to generate aerosols, which were injected into an environmental chamber for mouse exposure studies. We compared the effects of exposure to Salton Sea aerosols, as well as to known immunostimulatory reference materials. Acute 48-h and chronic 7-day exposures were com-pared, with lungs analyzed for inflammatory cell recruitment and gene expression.Results: Dust from sites nearest to the Salton Sea triggered lung neutrophil inflammation that was stronger at 48-h but re-duced at 7-days. This acute inflammatory profile and kinetics resembled the response to innate immune ligands LTA and LPS while distinct from the classic allergic response to Alternaria.Conclusion: Lung inflammatory responses to Salton Sea dusts are similar to acute innate immune responses, raising the pos-sibility that microbial components are entrained in the dust, promoting inflammation. This effect highlights the health risks at drying terminal lakes from inflammatory components in dust emissions from exposed lakebed.

Automated summary

Residents near the Salton Sea in southern California have a high incidence of asthma. Dust from the Salton Sea triggers lung inflammation in mice, resembling acute innate immune responses. This highlights the health risks of exposure to dust emissions from drying terminal lakes.