Nitric Oxide Signaling and Urinary Stone Disease in Mice Pilot Project

The overall goal of the Nitric Oxide Signaling and Urinary Stone Disease in Mice Pilot Project is to identify novel mechanisms contributing to initiation and progression of calcium deposits in ectopic tissues.

Our central hypothesis is that losses in nitric oxide (NO) signaling are major contributors to accelerated renal stone formation, and that re-activation of NO signaling will abrogate renal stone formation mice in vivo. Importantly, this pilot project also leverages ongoing NIH-funded work in the lab of Jordan D. Miller, Ph.D., including a clinical trial testing sGC activators in humans with calcific aortic valve disease.

The specific aims of the project are:

  • To determine whether reactivation of NO signaling with HMR1766 will abrogate renal stone formation in hypercholesterolemic mice given L-NAME in drinking water
  • To determine whether increasing NO signaling will abrogate renal calcium deposition in glyoxylate-induced nephrocalcinosis in mice.

Redifferentiation of cells to an osteoblast-like phenotype is thought to be central to the progression of calcified lesions in cardiovascular tissues. The vast majority of risk factors for development of cardiovascular calcification (aging, hypercholesterolemia, hypertension, smoking, and so on) are associated with increases in oxidative stress, which is ubiquitously associated with reductions in nitric oxide signaling. Little is known, however, regarding the role of nitric oxide signaling in the pathogenesis of ectopic calcium deposition in other tissues.

Dr. Miller's lab recently conducted a study in which hypercholesterolemic mice were given L-NAME in drinking water for six months. The initial focus was on cardiovascular tissue, where we found that chronic treatment of mice with L-NAME resulted in profound increases in cardiovascular calcification and aortic valve dysfunction.

After confirming our primary hypothesis that reducing NO bioavailability would accelerate cardiovascular calcification, we next sought to determine whether reducing NO signaling would result in induction of ectopic calcification in other tissues where calcified nodule formation is common. Importantly, we found that reducing NO signaling resulted in dramatic increases in calcium deposition in our mice's kidneys.

Thus, we believe we have identified a novel animal model of nephrocalcinosis in which to test therapeutic interventions aimed at slowing initiation and progression of renal stone formation.

Finally, we have discovered that reactivation of sGC using anthranilic acid derivatives (such as HMR1766) slows progression of cardiovascular calcification and aortic valve dysfunction in hypercholesterolemic mice. Importantly, little is known regarding the therapeutic efficacy of increasing nitric oxide bioavailability in the context of renal stone formation.