Ocular inoculation of toad venom: toxic cataract and proteomic profiling

To report a singular case of cataract caused by toad venom inoculation and to scrutinize the pathological mechanisms through proteomic sequencing of the lens specimen.

A young Chinese male presented with progressively deteriorating vision in his right eye subsequent to a history of toad venom inoculation. He was diagnosed with a toxic cataract, and underwent phacoemulsification cataract surgery. Anterior capsule, nucleus, and cortex specimens from the patient (designated as PT_CAP, PT_PHACO, and PT_CTX, respectively) and age-related cataract controls (C_CAP, C_PHACO, and C_CTX, respectively) were collected and subjected to 4D label-free quantitative proteomics.

A multitude of differentially expressed proteins (DEPs) were identified in the patient's lens compared to those in the controls. Specifically, a total of 204 DEPs were identified in PT_CAP compared to C_CAP, with MYH6, MYL2, MYL3, STAT1, and ANK1 among the foremost regulated DEPs. The DEPs of PT_CAP were principally affiliated with functions including "transportation of small molecules," "regulation of metal ion transport," and "import into cell." A sum of 109 DEPs were delineated in PT_CTX compared to C_CTX, with TPM1 among the top-10 downregulated DEPs. Ninety-five DEPs were pinpointed in PT_PHACO compared to C_PHACO, with hexokinase among the top 10 downregulated DEPs. These proteins were ascertained to be linked with Na⁺/K⁺-ATPase activity.

This study introduced the first documented case of toxic cataract caused by toad venom inoculation. Proteomic sequencing indicated a correlation between cataract and alterations in Na⁺/K⁺-ATPase activity, providing insights for the clinical management of ocular toad venom inoculation in subsequent cases.