Autosomal recessive polycystic kidney disease (
ARPKD) is a monogenic disease characterized by development of hepatorenal
cysts, pericystic
fibrosis, and
inflammation. Previous studies show that mast cell (MC) mediators such as
histamine induce proliferation of cholangiocytes. We observed robust MC accumulation around liver
cysts, but not kidney
cysts, in
polycystic kidney (PCK) rats (an animal model of
ARPKD). Therefore, we hypothesized that MCs contribute to hepatic
cyst growth in
ARPKD. To test this hypothesis, we treated PCK rats with 1 of 2 different MC stabilizers,
cromolyn sodium (CS) or
ketotifen, or saline. The CS treatment decreased MC degranulation in the liver and reduced serum
tryptase (an MC granule component). Interestingly, we observed an increase in liver to
body weight ratio after CS treatment paralleled by a significant increase in individual
cyst size. Hepatic
fibrosis was not affected by CS treatment. The CS treatment increased hepatic
cyst wall epithelial cell (CWEC) proliferation and decreased cell death.
Ketotifen treatment also increased hepatic
cyst size. In vitro, CS treatment did not affect proliferation of isolated hepatic CWECs from PCK rats. In contrast, CS decreased kidney to
body weight ratio paralleled by a significant decrease in individual
cyst size. The percentage of kidney to
body weight ratio was strongly correlated with serum
renin (an MC granule component).
Ketotifen did not affect kidney
cyst growth. Collectively, these data suggest that CS affects hepatic and renal
cyst growth differently in PCK rats. Moreover, CS may be beneficial to renal cystic disease but may exacerbate hepatic
cyst growth in
ARPKD.