Lipoic Acid Supplement for Cystine Stone

Cystinuria is a rare inherited autosomal recessive disorder of the kidney that is the result of a defect in the dibasic amino acid transporter in the renal proximal tubule and small intestine. Supersaturation of cystine in the urine produces crystals that precipitate and form calculi, which can be a cause of obstruction, infection, and chronic kidney disease (Chillarón 2010). One potential therapeutic is a thiol-containing compound alpha-lipoic acid (thioctic acid, 5-(1,2-dithiolan-3- yl) pentanoic acid, ALA). It is an over-the-counter supplement with antioxidant property. Once ALA is transported into the cell, it is reduced to dihydrolipoic acid (DHLA). Both ALA and DHLA have direct antioxidant activity (Scholich 1989), and they can regenerate endogenous antioxidants including ascorbic acid and vitamin E. It can also increase intracellular coenzyme Q10 and glutathione levels. ALA and DHLA also have additional biochemical effects as metal chelators, reactive oxygen species scavengers, and modulators of signaling transduction of several pathways (Gomes 2014). While the potential therapeutic effects of ALA have been studied in a number of diseases including, for example, Alzheimer's disease, obesity, cardiovascular disease, hypertension, and several cancers (Gomes 2014), the efficacy of ALA has been best studied in type 2 diabetic peripheral neuropathy (Ziegler 2011). In our lab, results from a mouse model of cystinuria show that ALA markedly slows the initiation of cystine stone formation as well as the growth of existing stones. Given this history in clinical medicine and, most importantly, based upon our positive findings of ALA effectiveness in a mouse model of cystinuria, we propose a pilot study on the use of this molecule in cystinuric patients.