Cataracts affect an estimated 24 million people in the United States annually and account for ~50 million cases of blindness worldwide. Although surgical cataract extraction is a reliable procedure that substantially improves visual acuity in 90% of cases, it places a large financial burden on healthcare systems. In the United States alone, the annual direct cost of cataract treatment is over $4.5 billion, higher than the combined costs to treat glaucoma, advanced macular degeneration, and diabetic retinopathy. Moreover, in much of the developing world, surgical intervention is simply not accessible for patients. Cataracts are caused when accumulated damage to the major lens crystallin proteins including ?-crystallin (cryAB), causes their unfolding and subsequent assembly into insoluble amyloids. There are no approved therapies to cure or reverse cataracts. Pharmacological chaperones are small molecules that bind and stabilize the native form of a protein. Our research team, in collaboration with chemist Dr. Jason Gestwicki (UCSF) and ophthalmologist Dr. Usha Andley (Washington University), recently developed a novel differential scanning fluorimetry (DSF) platform and identified molecules that stabilize the native fold of cryAB. Employing a small molecule, from this screen, we were able to demonstrate 1) prevention of the aggregation of cryAB and fully dis-assembled pre-formed aggregates in vitro; and 2) an ophthalmic solution of the hit molecule, compound 29 completely restored transparency to the eyes of a mouse model of severe cataract. Remarkably, this effect occurred after only 2 weeks of topical treatment, mirroring the reversal kinetics observed in vitro. To further develop this discovery, we will:
Aim 1. Design and synthesize an initial focused library of 30 pharmacological, small molecule chaperones to destabilize crystallin amyloid.
Aim 2. Screen and select small-molecule chaperones in vitro by assessing efficacy and therapeutic index. Iterate library as required.
Aim 3. Screen and select compounds in vivo for efficacy in a murine age-related cataract model as well as hereditary cataract model.
Cataract is the most common form of vision loss worldwide, impacting the vision of 24 million individuals in the US and >100 million worldwide. In this proposal, we will pursue a safe, effective, topical treatment for the reversal of cataracts.
