ABSTRACT BOYD-SHIWARSKI
The purpose of this R03 proposal is to develop pilot studies using new research methodology and technology to
investigate how dietary potassium (K+) deficiency leads to kidney injury. It is well known that dietary K+ deficiency
leads to hypertension, cardiovascular disease, as well as chronic kidney disease. My NIDDK K08 research was
funded to study how K+ deficiency alters proteins in the distal convoluted tubule leading to salt-sensitive
hypertension. In addition to hypertension, we observed that K+ deficient mice develop kidney injury with a
decrease in the glomerular filtration rate (GFR) and an increase in inflammatory markers. It has been proposed
that K+ deficiency causes kidney injury through activation of ammoniagenesis in the proximal tubule, yet the link
between hypokalemic-induced ammoniagenesis and kidney injury remains obscure. Our preliminary results in
K+ deficient mice have shown an increase in ammoniagenesis, an increase in complement activation, an increase
in inflammatory markers, and an increase in fibrosis. However, it is unclear whether the kidney injury is due to
local effects within proximal tubule cells, or due to an extra-renal immune or endocrine response. To isolate the
direct effects of low K+ on the proximal tubule we propose to develop and optimize two cellular model systems.
1) The first is optimizing a 2D permeable support proximal tubule model. This 2D polarized cellular model is the
current standard for studying proximal tubule cells in culture systems. 2) The second is developing a tubule-
scaffold using 3D bioprinted collagen that can be seeded with proximal tubule cells to recapitulate the 3D
environment with tubular constraints, laminar flow, and mechanical forces—factors all known to play a critical
role in proximal tubule differentiation and physiology. By developing these two cellular model systems we intend
to isolate the direct effects of low K+ on the proximal tubule, including the effects on ammoniagenesis and
activation of the de novo immune response. The results from this grant will advance our understanding of how
the Western diet, which is deficient in potassium, may increase susceptibility to kidney injury. Additionally, these
results will generate publications, facilitate independence, and form the foundation for my R01 application.