8-epi-prostaglandin-f2alpha and Kidney-Calculi

A number of animal models have been developed to investigate calcium oxalate (CaOx) nephrolithiasis. Ethylene glycol (EG)-induced hyperoxaluria in rats is most common, but is criticized because EG and some of its metabolites are nephrotoxic and EG causes metabolic acidosis. Both oxalate (Ox) and CaOx crystals are also injurious to renal epithelial cells. Thus, it is difficult to distinguish the effects of EG and its metabolites from those induced by Ox and CaOx crystals. This study was performed to investigate hydroxy-L-proline (HLP), a common ingredient of many diets, as a hyperoxaluria-inducing agent. In rats, HLP has been shown to induce CaOx nephrolithiasis in only hypercalciuric conditions. Five percent HLP mixed with chow was given to male Sprague-Dawley rats for 63 days, resulting in hyperoxaluria, CaOx crystalluria, and nephrolithiasis. Crystal deposits were surrounded by ED-1-positive inflammatory cells. Cell injury and death was followed by regeneration, as suggested by an increase in proliferating cell nuclear antigen-positive cells. Both osteopontin (OPN) and CD44 were upregulated. Staining for CD44 and OPN was intense in cells lining the tubules that contained crystals. Along with a rise in urinary Ox and lactate dehydrogenase, there were significant increases in 8-isoprostane and hydrogen peroxide excretion, indicating that the oxidative stress induced cell injury. Thus, HLP-induced hyperoxaluria alone can induce CaOx nephrolithiasis in rats.

Topics: Animals; Calcium; Calcium Oxalate; Creatinine; Dinoprost; Disease Models, Animal; Gene Expression Regulation; Hyaluronan Receptors; Hydrogen Peroxide; Hydroxyproline; Hyperoxaluria; Immunohistochemistry; Kidney Calculi; Kidney Tubules; L-Lactate Dehydrogenase; Male; Osteopontin; Oxalates; Rats; Rats, Sprague-Dawley; Sialoglycoproteins

Crystal formation and retention are critical events for the formation of kidney stones. Oxalate and calcium oxalate (CaOx) crystals are injurious to renal epithelium, and membranes of injured cells promote crystal adherence and retention. Calcium phosphate (CaP) is the most common crystal in both urine and stones, most likely to form in the early segments of the nephron and can nucleate CaOx in a metastable solution. We hypothesized that CaP can also injure the renal epithelial cells.. We exposed proximal tubular origin line derived from pig proximal tubules (LLC-PK1), and collecting duct origin Madin-Darby canine kidney (MDCK) cell lines to various concentrations of Brushite (Br) crystals and investigated staining with Trypan Blue and the release of lactate dehydrogenase (LDH) into the medium as an indicator of injury. In order to determine the involvement of reactive oxygen species, we also measured LDH release in the presence of superoxide dismutase (SOD) and production of hydrogen peroxide (H2O2) and 8-isoprostane (8-IP) in the presence of the catalase.. Exposure to Br crystals was associated with LDH release by both cell types, induced the production of H2O2 and 8-IP. Presence of SOD and catalase reduced LDH release as well as staining with trypan blue. Catalase was also associated with reduced production of H2O2 and 8-IP.. Brushite crystals are injurious to cells of both the proximal tubules as well as collecting ducts. Injury is mediated by reactive oxygen species. We propose that CaP crystals can independently interact with renal epithelium, promote sites for crystal attachment, and then either grow into mature CaP stones or create sites for CaOx crystal nucleation, retention, and stone development.

Topics: Animals; Calcium Phosphates; Catalase; Cell Line; Coloring Agents; Dinoprost; Dogs; Drug Synergism; Epithelium; Hydrogen Peroxide; Kidney; Kidney Calculi; L-Lactate Dehydrogenase; LLC-PK1 Cells; Reactive Oxygen Species; Staining and Labeling; Superoxide Dismutase; Swine; Trypan Blue