Inhibition of 5-lipoxygenase Decreases Renal Fibrosis and Progression of Chronic Kidney Disease

In inflammatory diseases, the 5-lipoxygenase (5-LO) pathway contributes to epithelial damage and fibrosis by catalyzing the production of leukotrienes (LTs). Antagonists of the 5-LO pathway are currently approved for use in patients and are well tolerated. We found that expression of 5-LO is strongly induced in three models of chronic kidney disease: unilateral ureteral obstruction (UUO), folate nephropathy, and an orthologous mouse model of polycystic kidney disease. Immunohistochemistry showed that macrophages are the dominant source of 5-LO. Zileuton, a US Food and Drug Administration-approved antagonist of 5-LO, significantly reduced fibrosis at 7 and 14 days after UUO; these findings were confirmed using a genetically modified [5-LO-associated protein-knockout ( Alox5ap)] mouse strain. Inhibition of 5-LO did not appear to change infiltration of leukocytes after UUO as measured by flow cytometry. However, fluorescence-lifetime imaging microscopy showed that 5-LO inhibitors reversed the glycolytic switch in renal tubular epithelial cells after UUO. Two downstream enzymes of 5-LO, LTA hydrolase (LTAH) and LTC synthase (LTCS), are responsible for the synthesis of LTB and cysteinyl LTs, respectively. Fibrosis was reduced after UUO in Ltc4s, but not Lta4h, mice. In contrast, using the folate nephropathy model, we found reduced fibrosis and improved renal function in both Ltc4s and Lta4h mice. In summary, our studies suggest that manipulation of the 5-LO pathway may represent a novel treatment approach for chronic kidney disease.