(4-(n-hydroxyamino)-2r-isobutyl-3s-methylsuccinyl)-l-phenylglycine-n-methylamide and Disease-Models--Animal

A pressure equalization tube placed within the tympanic membrane is the only clinically available method for inhibiting tympanic membrane regeneration. Problems associated with this include associated otorrhea, biofilm formation, medial migration of the tube, tube retention, induction of granulation tissue, and a small but significant rate of cholesteatoma. We aimed to demonstrate that a single administration of a sustained-release polymer formulation of KB-R7785 maintains tympanic membrane perforation for at least 6 months.. Sustained-release KB-R7785 was delivered within a novel polymer hydrogel to 20 mice with bilateral acute tympanic membrane perforations (a total of 40 perforations). The perforations were monitored at 3-month intervals until 9 months.. At 3 months, 90% of perforations were open (n=36/40). At 6 months, 75% of perforations were open (total n=30/40). At 9 months, 22.5% of perforations were open (total n=6/40). The majority of tympanic membrane perforations (75%) were open (not healed) beyond 6 months and close (fully healed) prior to 9 months (77.5%). Once healed, tympanic membranes resembled their normal histological appearance.. This study demonstrates that a single administration of a sustained-release polymer formulation of KB-R7785 inhibits tympanic membrane regeneration for 6-9 months.

Topics: Animals; Delayed-Action Preparations; Disease Models, Animal; Glycine; Hydroxamic Acids; Male; Mice; Mice, Inbred CBA; Regeneration; Tympanic Membrane Perforation

We aim to explore the role of epidermal growth factor (EGF) ligand shedding in tympanic membrane wound healing and to investigate the translation of its modulation in tissue engineering of chronic tympanic membrane perforations. Chronic suppurative otitis media (CSOM) is an infected chronic tympanic membrane perforation. Up to 200 million suffer from its associated hearing loss and it is the most common cause of pediatric hearing loss in developing countries. There is a need for nonsurgical treatment due to a worldwide lack of resources. In this study, we show that EGF ligand shedding is essential for tympanic membrane healing as it's inhibition, with KB-R7785, leads to chronic perforation in 87.9% (n=58) compared with 0% (n=20) of controls. We then show that heparin binding-EGF-like growth factor (5 μg/mL), which acts to shed EGF ligands, can regenerate chronic perforations in mouse models with 92% (22 of 24) compared with 38% (10 of 26), also with eustachian tube occlusion with 94% (18 of 19) compared with 9% (2 of 23) and with CSOM 100% (16 of 16) compared with 41% (7 of 17). We also show the nonototoxicity of this treatment and its hydrogel delivery vehicle. This provides preliminary data for a clinical trial where it could be delivered by nonspecialist trained healthcare workers and fulfill the clinical need for a nonsurgical treatment for chronic tympanic membrane perforation and CSOM.

Topics: Animals; Biocompatible Materials; Chronic Disease; Disease Models, Animal; Drug Delivery Systems; ErbB Receptors; Eustachian Tube; Evoked Potentials, Auditory, Brain Stem; Glycine; Heparin-binding EGF-like Growth Factor; Hydroxamic Acids; Ligands; Male; Mice; Otitis Media, Suppurative; Otoacoustic Emissions, Spontaneous; Polymers; Regeneration; Tympanic Membrane Perforation

Topics: Animals; Brain; Cerebrovascular Circulation; Disease Models, Animal; Enzyme Inhibitors; Extracellular Matrix; Female; Glycine; Hemodynamics; Humans; Hydroxamic Acids; Infarction, Middle Cerebral Artery; Intracranial Arteriosclerosis; Male; Matrix Metalloproteinase 1; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Matrix Metalloproteinases; Mice; Phenylalanine; Thiophenes; Treatment Outcome

G-protein-coupled receptor (GPCR) agonists are well-known inducers of cardiac hypertrophy. We found that the shedding of heparin-binding epidermal growth factor (HB-EGF) resulting from metalloproteinase activation and subsequent transactivation of the epidermal growth factor receptor occurred when cardiomyocytes were stimulated by GPCR agonists, leading to cardiac hypertrophy. A new inhibitor of HB-EGF shedding, KB-R7785, blocked this signaling. We cloned a disintegrin and metalloprotease 12 (ADAM12) as a specific enzyme to shed HB-EGF in the heart and found that dominant-negative expression of ADAM12 abrogated this signaling. KB-R7785 bound directly to ADAM12, suggesting that inhibition of ADAM12 blocked the shedding of HB-EGF. In mice with cardiac hypertrophy, KB-R7785 inhibited the shedding of HB-EGF and attenuated hypertrophic changes. These data suggest that shedding of HB-EGF by ADAM12 plays an important role in cardiac hypertrophy, and that inhibition of HB-EGF shedding could be a potent therapeutic strategy for cardiac hypertrophy.

Topics: ADAM Proteins; ADAM12 Protein; Angiotensin II; Animals; Aorta, Thoracic; Cardiomegaly; Disease Models, Animal; Disintegrins; Epidermal Growth Factor; ErbB Receptors; Glycine; GTP-Binding Proteins; Heart Ventricles; Heparin-binding EGF-like Growth Factor; Hydroxamic Acids; Hypertension; Intercellular Signaling Peptides and Proteins; Male; Membrane Proteins; Metalloendopeptidases; Phenylephrine; Protease Inhibitors; Protein Processing, Post-Translational; Rats; Signal Transduction; Systole; Transcriptional Activation