Pseudomonas aeruginosa infection liberates transmissible, cytotoxic prion amyloids

Abstract

Patients who recover from pneumonia subsequently have elevated rates of death after hospital discharge as a result of secondary organ damage, the causes of which are unknown. We used the bacterium , a common cause of hospital-acquired pneumonia, as a model for investigating this phenomenon. We show that infection of pulmonary endothelial cells by induces production and release of a cytotoxic amyloid molecule with prion characteristics, including resistance to various nucleases and proteases. This cytotoxin was self-propagating, was neutralized by anti-amyloid Abs, and induced death of endothelial cells and neurons. Moreover, the cytotoxin induced edema in isolated lungs. Endothelial cells and isolated lungs were protected from cytotoxin-induced death by stimulation of signal transduction pathways that are linked to prion protein. Analysis of bronchoalveolar lavage fluid collected from human patients with pneumonia demonstrated cytotoxic activity, and lavage fluid contained amyloid molecules, including oligomeric τ and Aβ. Demonstration of long-lived cytotoxic agents after infection may establish a molecular link to the high rates of death as a result of end-organ damage in the months after recovery from pneumonia, and modulation of signal transduction pathways that have been linked to prion protein may provide a mechanism for intervention.-Balczon, R., Morrow, K. A., Zhou, C., Edmonds, B., Alexeyev, M., Pittet, J.-F., Wagener, B. M., Moser, S. A., Leavesley, S., Zha, X., Frank, D. W., Stevens, T. infection liberates transmissible, cytotoxic prion amyloids.

Infection‐induced endothelial amyloids impair memory

“…We previously reported that infection elicits the endothelial production of cytotoxic amyloids (22,53), which can be detected in the BALF of pneumonia patients. Neutralizing these amyloids alleviates cerebral endothelial disruption and rescues synaptic plasticity (23).…”

“…Cytotoxic supernatant was prepared and collected using previously described methods (21,22). Briefly, a colony-forming unit (CFU) per milliliter ratio of 2 3 10 8 CFU/ml at optical density (OD) 540 for both P. aeruginosa strain PA103 and the negative control strain DPcrV was previously determined and used.…”

“…We clarified the homogenates by centrifugation and then collected the supernatants. We then added sarkosyl to each supernatant to a final concentration of 1%, incubated it for 60 min at 37°C, and then pelleted it at 200,000 g for 2 h. Immunoblot studies were performed with the reconstituted pellets following standard procedures (22). Blots were probed with T22, A11, and MOAB-2 (Novus Biologicals, Centennial, CO, USA) antibodies.…”

“…Brain accumulation of amyloid and tau proteins correlates with various forms of neurologic dysfunction (13)(14)(15)(16) and can contribute to pathology in the majority of dementia and memory-deficit cases (17,18). We recently showed that the Pseudomonas aeruginosa type III secretion system (T3SS) and exoenzyme effectors acutely induce pulmonary endothelial production and release of cytotoxic amyloid and tau proteins into the airways and blood of ICU patients (19)(20)(21)(22). The cytotoxins are detectable in the bronchoalveolar lavage fluid (BALF), plasma, and cerebrospinal fluid (CSF) of patients who tested positive for monomicrobial nosocomial pneumonia (23), suggesting that lung-derived amyloids could injure brain function.…”

“…The cytotoxins are detectable in the bronchoalveolar lavage fluid (BALF), plasma, and cerebrospinal fluid (CSF) of patients who tested positive for monomicrobial nosocomial pneumonia (23), suggesting that lung-derived amyloids could injure brain function. Importantly, these amyloids share features of prions; they ABBREVIATIONS: Ab, amyloid b; ACSF, artificial CSF; AMPA, a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid; BALF, bronchoalveolar lavage fluid; CFU, colony-forming unit; CSF, cerebrospinal fluid; FV, fiber volley; ICU, intensive care unit; ICV, intracerebroventricular; LTP, longterm potentiation; NMDA, N-methyl-D-aspartate; PA103, Pseudomonas aeruginosa isolated from patient 103; DPcrV, mutant strain of P. aeruginosa lacking a functional type 3 secretion system needle tip complex; Q1, quadrant 1; T3SS, type III secretion system are heat stable, RNase and DNase insensitive, protease resistant, transmissible, and self-replicating (22). In this study, we tested the hypothesis that lung infection elicits endothelium-derived neurotoxins that impair brain function, which depends on: 1) virulent bacterial infection, 2) virulence factors (e.g., T3SS), and 3) amyloid and tau proteins.…”