Identifying Aerosolized Cyanobacteria as an Environmental Risk Factor for ALS using Human Bronchoalveolar Lavage and Nasal Swab Specimens (P4.449)

Objective: To determine if aerosol is a potential route of cyanobacteria (CB) exposure in humans, and a possible risk factor for neurodegeneration in amyotrophic lateral sclerosis (ALS).

Background: Exposure to the CB toxin β-N-Methylamino-L-alanine (BMAA) has been implicated as an environmental risk factor for ALS. Our earlier epidemiologic studies of waterbodies with CB blooms in Northern New England suggest that inhalation of CB toxins may be a possible mode for human exposure.

Design/Methods: Seventeen non-ALS participants undergoing diagnostic bronchoscopy from Dartmouth-Hitchcock Medical Center consented to donate right upper lobe BALF and/or NS specimens. BALF samples were processed using standard cytocentrifuge methods and aliquots were reserved for nested 16s rDNA polymerase chain reaction (PCR). BALF and NS slides were analyzed using fluorescence microscopy (FM) to identify CB cells expressing phycocyanobilin pigments. “Fiji” software was used to analyze images for CB using a macro developed to measure fluorescent particles with ≥95% circularity for area and feret diameter. Purified CB was used as a positive control and analyzed following the same protocol as BALF and NS samples.

Results: 70.5% of BALF samples tested positive for CB using PCR. 91.6% of the PCR-positive BALF samples had CB detectable by FM, compared to only 20% of the PCR-negative samples. Independent samples t-tests found no significant differences between feret diameter of NS CB cells (Mean=2.85μm, SD=0.760μm) versus controls (Mean=3.19μm, SD=0.767μm); p= 0.486; and area of NS CB cells (Mean=4.48μm², SD=2.91μm²) versus control CB cells (Mean=5.82μm², SD=2.71μm²); p= 0.245.

Conclusions: These data suggest that humans may inhale aerosolized CB which can be harbored in the nostrils and, in some cases, the lungs. This is consistent with the hypothesis that aerosol may be a significant route of CB transmission. With chronic exposure, we postulate that this could represent an environmental risk factor for ALS.

Study Supported by: Diamond Research Development Award - Neurology, Dartmouth-Hitchcock Medical Center

Disclosure: Dr. Facciponte has nothing to disclose. Dr. Bough has nothing to disclose. Dr. Rauh has nothing to disclose. Dr. Carroll has nothing to disclose. Dr. Seidler has nothing to disclose. Dr. Dessaint has nothing to disclose. Dr. Vaickus has nothing to disclose. Dr. Henegan has nothing to disclose. Dr. Butt has nothing to disclose. Dr. Andrew has nothing to disclose. Dr. Stommel has nothing to disclose.