Vitamin E Efficacy in HI/HA

Summary

Congenital hyperinsulinism (HI) is a rare disorder of pancreatic beta cell insulin secretion that causes persistent and severe hypoglycemia starting at birth. Hyperinsulinism/hyperammonemia (HI/HA) syndrome is the second most common type of congenital HI and is caused by activating mutations in glutamate dehydrogenase (GDH). Patients with HI/HA exhibit fasting hyperinsulinemic hypoglycemia, protein-induced hypoglycemia, hyperammonemia, seizures, and intellectual disability independent of hypoglycemia. These effects result from abnormal GDH activity in the beta cells, liver and kidney cells, neurons, and astrocytes. The only available treatment for HI/HA syndrome is diazoxide, which acts on the beta cells to decrease insulin secretion but has no effect on GDH activity itself or on other cell types. Thus, there remains a significant unmet need for improved therapies for this disorder. Pre-clinical data show that vitamin E inhibits GDH activity in human cell lines and improves fasting hypoglycemia in a GDH HI mouse model. Pilot study data show that vitamin E supplementation with a moderate dose is well-tolerated in children and adults with HI/HA syndrome, while continuing diazoxide treatment. However, most subjects continued to exhibit protein-induced hyperinsulinemic hypoglycemia. We hypothesize that a higher vitamin E dose will inhibit GDH over-activity in subjects with HI/HA syndrome, resulting in improved hyperinsulinemic hypoglycemia, reduced blood ammonia concentration, and decreased seizure activity.

Timeline

Start

2022-11

Primary completion

2023-03

Completion

2023-03

Publications

• Background Palladino AA, Stanley CA. The hyperinsulinism/hyperammonemia syndrome. Rev Endocr Metab Disord. 2010 Sep;11(3):171-8. doi: 10.1007/s11154-010-9146-0.
• Background Snider KE, Becker S, Boyajian L, Shyng SL, MacMullen C, Hughes N, Ganapathy K, Bhatti T, Stanley CA, Ganguly A. Genotype and phenotype correlations in 417 children with congenital hyperinsulinism. J Clin Endocrinol Metab. 2013 Feb;98(2):E355-63. doi: 10.1210/jc.2012-2169. Epub 2012 Dec 28.
• Background Hsu BY, Kelly A, Thornton PS, Greenberg CR, Dilling LA, Stanley CA. Protein-sensitive and fasting hypoglycemia in children with the hyperinsulinism/hyperammonemia syndrome. J Pediatr. 2001 Mar;138(3):383-9. doi: 10.1067/mpd.2001.111818.
• Background Kelly A, Ng D, Ferry RJ Jr, Grimberg A, Koo-McCoy S, Thornton PS, Stanley CA. Acute insulin responses to leucine in children with the hyperinsulinism/hyperammonemia syndrome. J Clin Endocrinol Metab. 2001 Aug;86(8):3724-8. doi: 10.1210/jcem.86.8.7755.
• Background Stanley CA, Baker L. Hyperinsulinism in infancy: diagnosis by demonstration of abnormal response to fasting hypoglycemia. Pediatrics. 1976 May;57(5):702-11.
• Background Li M, Smith CJ, Walker MT, Smith TJ. Novel inhibitors complexed with glutamate dehydrogenase: allosteric regulation by control of protein dynamics. J Biol Chem. 2009 Aug 21;284(34):22988-3000. doi: 10.1074/jbc.M109.020222. Epub 2009 Jun 15.
• Background Treberg JR, Clow KA, Greene KA, Brosnan ME, Brosnan JT. Systemic activation of glutamate dehydrogenase increases renal ammoniagenesis: implications for the hyperinsulinism/hyperammonemia syndrome. Am J Physiol Endocrinol Metab. 2010 Jun;298(6):E1219-25. doi: 10.1152/ajpendo.00028.2010. Epub 2010 Mar 23.
• Background Ferslew KE, Acuff RV, Daigneault EA, Woolley TW, Stanton PE Jr. Pharmacokinetics and bioavailability of the RRR and all racemic stereoisomers of alpha-tocopherol in humans after single oral administration. J Clin Pharmacol. 1993 Jan;33(1):84-8. doi: 10.1002/j.1552-4604.1993.tb03909.x.

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