Late/chronic corneal injury following threat chemical exposure

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Abstract Exposure of Carbofuran (CF; a pesticide) and Chlorine (Cl2; a bleaching and warfare agent) to humans is a major public health issue. Over 3 million people exposed to CF/Cl2 show high ocular morbidity. A major gap in knowledge is lack of mechanistic data “how CF/Cl2 exposure causes corneal injury and vision loss”? We test a novel hypothesis that mTORC1-mediated dysfunctional autophagosome formation and lysosomal biogenesis are a dominant operating mechanism for corneal damage from exposure of these threat chemicals (CF/Cl2). Autophagy and lysosomal biogenesis play a key role in corneal homeostasis and transparency maintenance. Our hypothesis is based on a human-patient study identifying defective autophagy the cause of slow and progressive corneal thinning and vision loss in keratoconus patients. Pilot studies performed with mice and donor human corneas strongly supports our novel hypothesis. The main goal of this project is to test our hypothesis employing highly rigorous approach using 2 threat chemicals (CF and Cl2) and 2 animal species (C57BL/6J mice and New Zealand White rabbits) and applicability of postulated mechanism in human using donor human cornea derived organ culture and primary cell culture models using two entirely independent but integrated specific aims. Aim-1 defines clinical signs and underline mechanism of late/chronic corneal toxicity caused by CF exposure to the eye using 3 sub-aims: (1a) records clinical signs and changes in the phenotype and density of corneal epithelial, stromal keratocytes, and endothelial cells in CF +/- exposed eyes of live rabbits and mice in vivo every two weeks interval with slit-lamp, HRT3-RCM confocal, Specular, and Spectralis optical coherence tomography microscopy system until 6 months, (1b) defines the mechanism by analyzing autophagosomal and lysosomal signature genes (ATGs, LC3, SQSTM1/p62, LAMP1, mTORC1, TFEB, & vATPase) in CF +/- exposed corneas of 2 species collected at 1, 2, 4, and 6 months, and (1c) verifies applicability of postulated mechanism in human using cadaver corneas. Aim-2 defines clinical symptoms and underline mechanism of late/chronic corneal toxicity caused by Cl2 exposure to the eye using 3 sub-aims: (2a) records clinical signs and changes in the phenotype and density of corneal epithelial, stromal keratocytes, and endothelial cells in Cl2 +/- eyes of live rabbits and mice in vivo, (2b) elucidates Cl2-induced corneal damage by studying autophagosomal and lysosomal signatures stated in aim-1b in Cl2 +/- corneas of 2 species, and (2c) verifies applicability of mechanism in humans using control donor human corneas employing an experimental approach and techniques stated in Aim-1a-c. With proposed studies, we expect to define start time, extent, and duration of symptoms after CF and Cl2 exposure in live animals, role of mTORC1 mediated autophagic events in CF/Cl2 exposed corneas and signature autophagosomal and lysosomal genes linked to CF/Cl2 mediated corneal toxicity. Successful completion of studies is expected to fill many knowledge gaps and advance ocular counterACT field significantly.