Pharmaceutical Optimization of Peptide Toxins for Ion Channel Targets: Potent, Selective, and Long-Lived Antagonists of Kv1.3.

To realize the medicinal potential of peptide toxins, naturally occurring disulfide-rich peptides, as ion channel antagonists, more efficient pharmaceutical optimization technologies must be developed. Here, we show that the therapeutic properties of multiple cysteine toxin peptides can be rapidly and substantially improved by combining direct chemical strategies with high-throughput electrophysiology. We applied whole-molecule, brute-force, structure-activity analoging to ShK, a peptide toxin from the sea anemone Stichodactyla helianthus that inhibits the voltage-gated potassium ion channel Kv1.3, to effectively discover critical structural changes for 15× selectivity against the closely related neuronal ion channel Kv1.1. Subsequent site-specific polymer conjugation resulted in an exquisitely selective Kv1.3 antagonist (>1000× over Kv1.1) with picomolar functional activity in whole blood and a pharmacokinetic profile suitable for weekly administration in primates. The pharmacological potential of the optimized toxin peptide was demonstrated by potent and sustained inhibition of cytokine secretion from T cells, a therapeutic target for autoimmune diseases, in cynomolgus monkeys.

Evaluation of a collagen patch as a method of enhancing ventriculotomy healing in Japanese quail (Coturnix coturnix japonica).

OBJECTIVE: To assess the ability of a porcine submucosal collagen patch to enhance ventriculotomy healing in quail. STUDY DESIGN: Histologic assessment of wound repair after ventriculotomy. Animal Population-Eighteen adult Japanese quail. METHODS: All quail had a ventriculotomy through the caudoventral thin muscle. The quail were randomly assigned to 1 of 2 groups: group I (n = 9) had routine closure and group II (n = 9) had routine closure and the application of a porcine submucosal collagen patch over the serosal surface of the ventricular suture line. Three quail from each group underwent necropsy at 7, 14, and 21 days after surgery and healing of the ventriculotomy site was evaluated by microscopy. RESULTS: Ventricular mucosal epithelium was completely healed at 21 days postoperatively. Time to restoration of the ventricular submucosal integrity was variable in both groups. There was evidence of a gross or microscopic perforation in 4 quail in group II, which was statistically significant (P =.041). Quail with perforations had significantly elevated numbers of ventricular serosal lymphoid aggregates compared with those without perforations (P =.029). There were no other significant temporal differences between group I and group II for mortality or histopathologic grading of wound healing. CONCLUSIONS: A porcine collagen patch did not enhance ventriculotomy wound healing. Subjectively, the collagen patch might have contributed to perforation by the generation of a lymphocytic xenograft rejection response. CLINICAL RELEVANCE: Ventriculotomy can be safely performed using routine closure methods in healthy birds.